Exposure controlling device for camera

ABSTRACT

An exposure controlling device comprises, a controlling unit that controls a DC motor, a calculating unit that calculates a time period between a predetermined starting point and a point where a predetermined aperture area is obtained during the forward rotation of the DC motor, and a timer for counting the time period from the starting point. The controlling unit controls, at the time of an exposure, the DC motor to rotate reversely for a predetermined time period at a first step, to rotate forward to open shutter blades of a lens shutter at a second step and to rotate reversely to close the shutter blades at a third step.

BACKGROUND OF THE INVENTION

The present invention relates to an exposure controlling device for alens shutter camera.

An exposure controlling device, which drive the shutter blades of a lensshutter by means of a DC motor, has been used in a conventional lensshutter camera. This type of lens shutter does not have only a functionof a shutter for determining a shutter speed corresponding to a timevalue Tv, but also a function of an aperture stop for determiningaperture area that corresponds to an aperture value Av. And therefore,both of the shutter speed and the aperture area of the shutter must beaccurately controlled.

The shutter speed is controlled by using a timer. On the other hand, theconventional exposure controlling devices are classified into two typesfrom a view point of the aperture control. In the first type, a devicedetermines the aperture area by detecting driving amount of the DC motorby a detector such as a pulse encoder, because the driving amountcorresponds to the aperture area. The pulse encoder comprises a rotationdisk having slits arranged along a circumferential direction and aphotointerrupter that outputs pulse signal in accordance with therotation of the rotation disk due to the rotation of the DC motor. Thefirst type device detects the aperture area based on the detected pulsecount and controls the DC motor.

In the second type, a device controls the DC motor with detecting timeperiod for driving the DC motor from a predetermined starting point. Thetime period is also related to the aperture area, the second type devicedetects the time period by a timer and controls the DC motor based onthe detected time period.

In order to increase the accuracy of the exposure, it is required torise a resolution of the detection, i.e., to use a fine encoder or afine timer. However, the fine encoder requires a fine pitch rotationdisk, it rises a production cost of the encoder.

On the other hand, although a fine timer is easier to construct than thefine encoder, an initial position from which the shutter starts torotate should be kept at the same point to maintain the constantcondition of the motor rotation. If the initial point is varied forphotographings, the aperture area cannot be determined accurately and itcauses failure in photographs.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide the secondtype exposure controlling device, i.e., aperture area is determined bytime period (interval) of the motor rotation, which can accuratelycontrol a lens shutter.

In order to achieve the above object, the present invention presents anexposure controlling device which allows to accurately determine theaperture area according to the time period by setting the shutter bladesunder the same condition before the exposure.

The exposure controlling device of the present invention comprises, acontrolling unit that controls a DC motor, a calculating unit thatcalculates a time period between a predetermined starting point and apoint where a predetermined aperture area is obtained during the forwardrotation of the DC motor, and a timer for counting the calculated timeperiod. The controlling unit controls, at the time of an exposure, theDC motor to rotate reversely for a predetermined time period at a firststep, to rotate forward to open shutter blades of a lens shutter at asecond step and to rotate reversely to close the shutter blades at athird step.

In particular case, the motion of the lens shutter is mechanicallylimited at both ends of the actuation range of the shutter blades, andthe controlling unit controls, before the exposure, the DC motor to setthe shutter blades at the one end where the shutter blades are fullyclosed.

In further particular case, the controlling unit controls the DC motorto rotate reversely at the end of the time period. In the otherparticular case, the controlling unit controls a strobe to flash at theend of the time period.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view and a block diagram of an example of amechanical structure of a camera, to realize a method of focusing for azoom lens camera of the present embodiment;

FIG. 2 is a schematic view of a structure of an example of a zoom lenssystem according to the method of focusing of the present embodiment;

FIG. 3 is a graphic representation of an example of lens movementcontrol according to the method of focusing of the present embodiment;

FIG. 4 is a graphic representation of another example of lens movementcontrol according to the method of focusing of the present embodiment;

FIG. 5 is a graphic representation of another example of lens movementcontrol according to the method of focusing of the present embodiment;

FIG. 6 is a graphic representation of another example of lens movementcontrol according to the method of focusing of the present embodiment;

FIG. 7 is a graphic representation of another example of lens movementcontrol according to the method of focusing of the present embodiment;

FIG. 8 is an enlarged schematic perspective view which shows part of azoom lens barrel according to the present embodiment;

FIG. 9 is a schematic perspective view of the zoom lens barrel shown inFIG. 8, in a different condition;

FIG. 10 is an enlarged exploded perspective view of a part of the zoomlens barrel;

FIG. 11 is a schematic perspective view illustrating a state where anAF/AE shutter unit of the zoom lens barrel is mounted to a first movingbarrel;

FIG. 12 is an exploded perspective view illustrating main parts of theAF/AE shutter unit of the zoom lens barrel;

FIG. 13 is a schematic perspective view of an outline of a third movingbarrel of the zoom lens barrel;

FIG. 14 is a front elevational view of a fixed lens barrel block of thezoom lens barrel;

FIG. 15 is a sectional view of an upper part of the zoom lens barrel ina most extended state;

FIG. 16 is a sectional view of an upper part of the zoom lens barrel,when in a housed state, illustrating essential parts;

FIG. 17 is a sectional view of an upper part of the zoom lens barrel,illustrating essential parts in a maximum extended state;

FIG. 18 is a sectional view of an upper part of the zoom lens barrel ina housed state;

FIG. 19 is an exploded perspective view of the overall structure of thezoom lens barrel;

FIG. 20 is a block diagram of a controlling system to control anoperation of the zoom lens barrel;

FIG. 21 is a sectional view illustrating a state when the zoom lensbarrel is positioned close to a "wide" end, and further a state before arelease button is released;

FIG. 22 is a sectional view illustrating a state when the zoom lensbarrel is positioned close to a "wide" end, and further a stateimmediately after the release button is released;

FIG. 23 is a sectional view illustrating a state when an external forcein the direction of the camera body is made to the front of the firstmoving barrel, and a whole lens barrel unit is retracted into the camerabody, and the a rear lens group collides with a film F;

FIG. 24 is a schematic view illustrating loci of movements of the frontlens group and the rear lens group;

FIG. 25 is a schematic view illustrating movements of the rear lensgroup with respect to the front lens group;

FIG. 26 is a front elevational view of an example of an embodiment of azoom lens camera according to the present embodiment;

FIG. 27 is a rear elevational view of the zoom lens camera shown in FIG.26;

FIG. 28 is a plan view of the zoom lens camera shown in FIG. 26;

FIG. 29 is a block diagram of the main parts of a control system of thezoom lens camera of the present embodiment;

FIG. 30 is a schematic view of a structure of a zoom code plate andbrushes, and a structure of detection of a position of a zoom code incontact with the brushes to detect a position of the lenses of the zoomlens camera;

FIG. 31 is a schematic view illustrating an example of an electroniccircuit to detect the zoom code, in contact with the brushes, as avoltage;

FIG. 32 is a table illustrating conversions of voltage, obtained throughcontact with the brushes, into a code;

FIG. 33 is a schematic view illustrating an example of an electroniccircuit of a strobe; FIG. 34 is a schematic view illustrating movementof the front lens group and the rear lens group of the zoom lens camera;

FIG. 35 is a schematic view illustrating movement sequences of a wholeunit driving motor and a rear lens group driving motor during exposure(i.e., during focusing) of the zoom lens camera;

FIG. 36 is a schematic view illustrating movement sequences of the wholeunit driving motor and the rear lens group driving motor during lensreturn of the zoom lens camera;

FIG. 37 is an exploded perspective view of a peripheral structure of therear lens group of the zoom lens barrel;

FIG. 38 is a plan view of the main parts of an example of an initialposition detecting device of the rear lens group of the presentembodiment;

FIG. 39 is a sectional view of the initial position detecting device ofthe rear lens group, at a state when the rear lens group is at theinitial position;

FIG. 40 is a sectional view of the initial position detecting device ofthe rear lens group, at a state when the rear lens group is not at theinitial position;

FIG. 41 is a flow chart of a main process of the zoom lens camera;

FIG. 42 is a flow chart of a reset process of the zoom lens camera;

FIG. 43 is a flow chart of an AF lens initialization process of the zoomlens camera;

FIGS. 44 and 45 show a flow chart of a lens housing process of the zoomlens camera;

FIG. 46 is a flow chart of a lens extension process of the zoom lenscamera;

FIG. 47 is a flow chart of a zoom "tele" movement process of the zoomlens camera;

FIG. 48 is a flow chart of a zoom "wide" movement process of the zoomlens camera;

FIG. 49 is a flow chart of a photographing process of the zoom lenscamera;

FIG. 50 is a flow chart of a main charging process of the zoom lenscamera;

FIG. 51 is a flow chart of a shutter initialization process of the zoomlens camera;

FIG. 52 is a flow chart of a zoom code input process of the zoom lenscamera;

FIG. 53 is a flow chart of an AF pulse confirmation process of the zoomlens camera;

FIG. 54 is a flow chart of an AF return process of the zoom lens camera;

FIG. 55 is a flow chart of a barrier closing process of the zoom lenscamera;

FIG. 56 is a flow chart of a barrier opening process of the zoom lenscamera;

FIG. 57 is a flow chart of a zoom driving process of the zoom lenscamera;

FIG. 58 is a flow chart of an AF two-stage extension process of the zoomlens camera;

FIG. 59 is a flow chart of a zoom return process of the zoom lenscamera;

FIG. 60 is a flow chart of a zoom return process and a zoom standbyconfirmation process of the zoom lens camera;

FIG. 61 is a flow chart of a photographing charging process of the zoomlens camera;

FIG. 62 is a flow chart of a focusing process of the zoom lens camera;

FIGS. 63, 64 and 65 show a flow chart of an exposure process of the zoomlens camera;

FIG. 66 is a flow chart of a lens return process of the zoom lenscamera;

FIG. 67 is a flow chart of a lens driving operation process of the zoomlens camera;

FIG. 68 is a flow chart of a test function process of the zoom lenscamera;

FIG. 69 is a flow chart of an AF pulse counting process of the zoom lenscamera;

FIG. 70 is a flow chart of a zoom driving check process of the zoom lenscamera;

FIG. 71 is a flow chart of an AF driving process of the zoom lenscamera;

FIG. 72 is a flow chart of a zoom pulse counting process of the zoomlens camera;

FIG. 73 is a flow chart of an AF driving check process of the zoom lenscamera;

FIG. 74 is a block diagram showing the general arrangement of the AEencoder of the embodiment when a rotating disk is positioned at aregular initial position;

FIG. 75 is a time chart of the exposure sequence of the embodiment inthe strobe no-emission mode;

FIG. 76 shows a relationship between a photointerrupter and a rotatingdisk when a shutter opens at a predetermined aperture A1;

FIG. 77 is a time chart of the exposure sequence of the embodiment inthe strobe emission mode;

FIG. 78 shows a relationship between a photointerrupter and a rotatingdisk when a shutter fully opens;

FIG. 79 shows a relationship between a photointerrupter and a rotatingdisk when a shutter is positioned at the irregular initial position;

FIG. 80 is a time chart of the exposure sequence of the embodiment inthe strobe no-emission mode when a shutter is positioned at an irregularinitial position before an exposure; and

FIG. 81 is a graph showing the relationship between the AE timer timeand the exposure value.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is an (essentially) schematic representation of various elementswhich comprise a zoom lens camera according to the present embodiment.More specific details of such a camera are described hereinafter withreference to FIGS. 8-103. Thus, although they may describe similarand/or identical parts, the reference numerals used in FIG. 1 are notidentical to those used in the other figures.

As shown in FIG. 1, a zoom lens barrel 410 is provided with a front lensgroup L1 of positive power and a rear lens group L2 of negative powershown in FIG. 1. On an outer periphery of a stationary ring 411, adriving ring 412 is rotatably supported, and on an inner peripherythereof, a front lens group supporting ring 413, which supports thefront lens group L1, and a rear lens group supporting ring 414, whichsupports the rear lens group L2, are engaged. On the stationary ring411, a linear guide groove 411a is formed parallel to an optical axis OAof the zoom lens barrel 410, and a radial pin 415, provided on the frontlens group supporting ring 413, is engaged with a lead groove 412aformed on an inner peripheral surface of the driving ring 412. Theradial pin 415 passes through the linear guide groove 411a to engagewith the lead groove 412a. On an outer periphery of the driving ring412, a gear 417 is fixedly engaged with a gear 419 of a whole unitdriving (whole unit moving) motor 418.

On the stationary ring 411, a linear guide groove 411b is formedparallel to the optical axis of the zoom lens barrel 410. A radial pin420, provided on the rear lens group supporting ring 414, engages withthe linear guide groove 411b. On the front lens group supporting ring413, a rear lens group driving (rear lens group moving) motor 421 and adriving screw 422 driven rotatably by the rear lens group driving motor421, are provided. The driving screw 422 engages with an anti-rotatingnut 423 provided on the rear lens group supporting ring 414.

In the above described structural arrangement, when the driving ring 412is rotatably driven by the whole unit driving motor 418, in accordancewith the relationship between the lead groove 412a and the linear guidegroove 411a, the front lens group supporting ring 413 (i.e., the frontlens group L1) moves in the optical axis direction. Since the rear lensgroup supporting ring 414 (i.e., the rear lens group L2) is secured tothe front lens group supporting ring 413 through the driving screw 422and the nut 423, the rear lens group supporting ring 414 moves togetherwith the front lens group supporting ring 413 in the optical axisdirection. Thus it can be understood that the whole unit driving motor418 moves both lens groups, i.e., the front and rear lens groups,together as a whole.

On the other hand, when the driving screw 422 is rotatably driven by therear lens group driving motor 421, the rear lens group supporting ring414 (i.e., the rear lens group L2) moves relatively to the front lensgroup supporting ring 413 (i.e., the front lens group L1). Thus it canbe understood that the rear lens group driving motor 421 is a motorwhich varies the distance between the rear lens group L2 and the frontlens group L1.

The whole unit driving motor 418 and the rear lens group driving motor421 are respectively controlled and driven by respective motorcontrolling circuits 425 and 426. The whole unit driving motor 418 isalso connected to a zoom finder 427 so that a field of view of thefinder varies when the whole unit driving motor 418 is actuated.

In the main body of the camera, a zoom operating device 431, a focusoperating device 432, an object distance measuring device 433 and aphotometering apparatus 434 are provided. The zoom operating device 431provides a zooming command, namely commands to move from a "wide"position to a "tele" position, or vice versa, to the zoom lens barrel410, i.e., the front lens group L1 and the rear lens group L2. The zoomoperating device 431 consists of, for example, a switch according to amomentary mechanical system. The focus operating device 432 consists of,for example, of a release button. When the focus operating device 432 isdepressed by a half-depression (half-step), object distance measurementinformation is input to the object distance measuring device 433 andphotometering information is input to the photometering apparatus 434.When the focus operating device 432 is fully depressed (full step), thefocusing operation commences, and a shutter 436, mounted to the frontlens group supporting ring 413, is operated via a AE motor controllingcircuit 435. The shutter 436 opens a shutter blade 436a for apredetermined time according to the photometering information outputfrom the photometering apparatus 434.

In the zoom lens camera as above described, when the zoom operatingdevice 431 is operated, the whole unit driving motor 418 is driven viaat least the whole unit driving motor controlling circuit 425, and thefront lens group L1 and the rear lens group L2 are moved as a whole. Therear lens group driving motor 421 may also be driven via the rear lensgroup driving motor controlling circuit 426. With the above structuralarrangement, it should be understood that the movement of the front lensgroup L1 and the rear lens group L2 by the zoom operating device 431 isnot operated under the conventional concept of zooming in which thefocal point does not move. When the zoom operating device 431 isoperated, the following two modes are available, namely:

1. a mode to move the front lens group L1 and the rear lens group L2, inthe optical axis direction, without varying the distance therebetween,by driving only the whole unit driving motor 418; and,

2. a mode to move the front lens group L1 and the rear lens group L2, inthe optical axis direction, while varying the distance therebetween, bydriving both the whole unit driving motor 418 and the rear lens groupdriving motor 421.

In mode 1, during the zooming operation it is impossible to focus on thesubject. However, this is not a problem in a lens- shutter type camera,since the image is not observed through the photographing opticalsystem, and it is sufficient to only be focused when the shutter isreleased. In mode 2, during the zooming operation, the front lens groupL1 and the rear lens group L2 are moved without consideration of whetherthe focal point moves, and when the shutter is released, focusing (focusadjusting) is carried out by moving both the whole unit driving motor418 and the rear lens group driving motor 421.

On the other hand, when the whole unit driving motor 418 is actuated bythe zoom operating device 431, the zoom finder 427 is driven so that thefinder field of view thereof is changed in accordance with the focallength set. Specifically, as the set focal length changes from a shortfocal length to a longer focal length, the finder field of view (angle)changes from a wider field of view to a narrower field of view. Thefinder field of view of course corresponds to a photographing imagesize. This kind of zoom finder is well known and is therefore not shown.

In the present embodiment, as mentioned above, when the zoom operatingdevice 431 is operated to set a focal length, the finder field of view(photographing image area) at the set focal length is observed throughthe zoom finder 427.

Further when the focus operating device 432 is operated in at least onepart of the focal length range set by the zoom operating device 431, thewhole unit driving motor 418 and the rear lens group driving motor 421are driven and subject focusing is performed. The movement of the frontlens group L1 and the rear lens group L2 by the whole unit driving motor418 and the rear lens group driving motor 421 is determined, not onlyusing subject distance information provided from the object distancemeasuring device 433, but also by using focal length information set bythe zoom operating device 431. In such a manner, when the focusoperating device 432 is operated, by moving both the whole unit drivingmotor 418 and the rear lens group driving motor 421, the position of thelenses can be flexibly controlled, i.e., the position of the lenses hasa degree of flexibility.

In theory, during an operation of the zoom operating device 431, themagnification of the finder and the focal length information are onlyvaried without driving neither the whole unit driving motor 418 nor therear lens group driving motor 421, and when the focus operating device432 is operated, both the whole unit driving motor 418 and the rear lensgroup driving motor 421 are moved simultaneously according to the focallength information and the subject distance information obtained by theobject distance measuring device 433 to move the front lens group L1 andthe rear lens group L2 to positions decided according to the focallength and the subject distance information.

The following discussion will illustrate several examples of a frontlens group L1, a rear lens group L2, and a controlling of movementthereof. Table 1 shows lens data regarding the front lens group L1 andthe rear lens group L2, and FIG. 2 is a drawing showing the structure ofthe lens groups. The lens data only shows a concrete example of theoptical system which is applicable to a two-lens group type zoom lensaccording to the present embodiment. The front lens group L1 consists offour lens groups having five lens elements, and the rear lens group L2consists of two lens groups having two lens elements (duplet).

In the following tables and the drawings (FIGS. 3 through 7), FNOrepresents the F number, f represents the focal length, ω represents thehalf angle of view, fB represents the back focal distance, ri representsthe curvature of radius of each lens surface, di represents thethickness of a lens or the distance between lenses, n represents therefractive index of the d-line, and ν represents the Abbe number.

                  TABLE 1                                                         ______________________________________                                        FNO = 1:3.9-10                                                                f = 39-102 (mm)                                                               ω = 28.4-12.0 (degrees)                                                 fB = 9.47-63.1 (mm)                                                           ______________________________________                                        Surface No.                                                                              ri      di           n     ν                                    ______________________________________                                        1          20.550  2.10         1.48749                                                                             70.2                                    2          42.627  1.65         --    --                                      3          -15.428 1.66         1.83400                                                                             37.2                                    4          -30.458 3.06         --    --                                      5          631.122 2.80         1.51633                                                                             64.1                                    6          -16.980 0.10         --    --                                      7          91.952  3.42         1.53996                                                                             59.5                                    8          -11.244 1.60         1.80400                                                                             46.6                                    9          -23.784 12.56-2.59   --    --                                      10         -42.469 2.50         1.58547                                                                             29.9                                    11         -26.490 5.04         --    --                                      12         -10.416 1.50         1.71299                                                                             53.9                                    13         -48.829 --           --    --                                      ______________________________________                                    

Surface 10 is an aspherical surface having rotational symmetry.

Aspherical Surface Data:

K=0.0, A4=5.96223*10⁻⁵, A6=2.52645*10⁻⁷,

A8=2.89629*10⁻⁹

The shape of the aspherical surface having rotational symmetry can begenerally expressed as follows:

    X=Ch.sup.2 /{1+ 1-(1+K)C.sup.2 h.sup.2 !.sup.1/2 }+A4h.sup.4 +A6h.sup.6 +A8h.sup.8 +A10h.sup.10 +

wherein, h represents a height above the axis,

X represents a distance from a tangent plane of an aspherical vertex,

C represents a curvature of the aspherical vertex(1/r),

K represents a conic constant,

A4 represents a fourth-order aspherical factor,

A6 represents a sixth-order aspherical factor,

A8 represents an eighth-order aspherical factor,

A10 represents a tenth-order aspherical factor.

Data regarding zooming is shown in Table 2. In Table 2, TL representsthe distance from the primary surface to the image surface, d_(1G-2G)represents the distance between the front lens group L1 and the rearlens group L2. The values of TL and d_(1G-2G) represent absolutepositions of the first lens group L1 and the second lens group L2 whenzooming while keeping the in-focus condition with respect to an objectat infinite distance, and the lens positions are realized by a cammechanism in a conventional zoom compact camera. Specifically, uponsetting a focal length by a zoom switch, the first lens group L1 and thesecond lens group L2 move to positions defined in Table 2 which aredetermined by the focal length set.

However, according to the zoom lens camera of the present embodiment,upon setting a focal length by the zoom operating device 431, the firstlens group L1 and the second lens group L2 do not move to positionsdefined in Table 2.

In Table 2, XA (f) represents the total movement distance of the firstlens group L1 and the second lens group L2 at a respective focal lengthby the whole unit moving motor 418 from reference positions thereof. Thereference positions (XA(f)=0) are defined by the positions of the lensgroups L1 and L2 when the lens groups are located at the shortest focallength (39 mm) while focusing on an object at infinity.

In Table 2, XB(f) represents the total movement distance of the secondlens group L2 with respect to the first lens group L1 at a respectivefocal length by the relative moving motor 421 from a reference positionof the rear lens group L2. The reference position (XB(f)=0) is definedas the position of the second lens group L2 when the lens groups L1, L2are located at the longest focal length (102 mm) while focusing on anobject at infinity.

The point is that the movement distances XA(f) and XB(f) are not givenjust by setting a focal length, but are given when the focus operatingdevice 432 is operated. Note that "0" in XA(f) and XB(f) representsreference positions and does not refer to stand-by positions of the lensgroups L1, L2 before the motors 418 and 421 are actuated. In otherwords, "0" in XA(f) and XB(f) does not mean that the motors 418 and 421are not driven when the focus operating device is operated.Mechanically, to realize a precise position control of the lens groups,it is preferred that the lens groups are positioned at waiting positionswhich are represented by negative values (positions moved in directionsopposite from the reference position) in Table 2 and are moved topositions shown in Table 2 upon operation of the focus operating devicefrom the waiting positions.

                  TABLE 2                                                         ______________________________________                                        f         TL     d.sub.1G-2G XA(f) XB(f)                                      ______________________________________                                        39        47.45  12.56       0     9.97                                       45        50.36  10.44       2.91  7.85                                       70        66.66  5.42        19.21 2.83                                       95        85.56  3.05        38.11 0.46                                       102       91.11  2.59        43.66 0                                          ______________________________________                                    

As described above, in the zoom lens camera according to the presentembodiment, the first lens group L1 and the second lens group L2 move topositions determined by set focal length information and detected objectdistance information by actuating the motors 418 and 421 using the zoomoperating device 431 and the focus operating device 432. Accordingly, itis possible to make zooming control and focusing control without usingthe cam mechanism by storing lens position data, consisting of acombination of stepped focal length information and stepped objectdistance information, in a memory, and digitally controlling the motors418 and 421 in accordance with the stored lens position data. Therefore,how to control the motors 418 and 421 in accordance with the informationin combination with the set focal length information and the detectedobject distance information is not within the scope of the main subjectof the present application. The following discussion illustrates fiveadvantageous examples of how to control the motors 418 and 421 (lensgroups L1 and L2). It is possible to selectively employ these controlsin accordance with the zoom lens of the present embodiment.

In the following examples XA represents movement due to the whole unitdriving motor, XB represents movement due to the rear lens group drivingmotor, (f) represents the function of the focal length, (u) representsthe function of the subject distance, and XA and XB respectivelyrepresent movement during focusing due to the whole unit driving motorand the rear lens group driving motor. Namely, XAmax represents themaximum movement during zooming and additional focusing due to the wholeunit driving motor, XA(f)max represents the maximum movement duringzooming due to the whole unit driving motor, ΔXF(u) represents themovement based only on subject distance regardless of the focal length,XBmax represents the maximum movement during zooming and additionalfocusing due to the rear lens group driving motor, and XB(f)maxrepresents the maximum movement during zooming due to the rear lensgroup driving motor.

EXAMPLE 1!

FIG. 3 is a first example of a front lens group L1 and a rear lens groupL2. In FIGS. 3 through 7, the length of the arrows of ΔXA and ΔXB aredrawn in a larger scale than the arrows of XA and XB.

In the present example, throughout the whole focal length range, set bythe zoom operating device 431, the total movement XA and the relativemovement of the rear lens group XB are given by the followingrelationships:

    XA=XA(f)+ΔXF(u)

    XB=XB(f)+ΔXF(u)

In other words, XA and XB are defined by the addition of a similarquantity of ΔXF(u), without having any relationship to the focal length.When the same amount of ΔXF(u) is added to XA and XB, in regard to thefunction of the subject distance (u), the distance of the rear lensgroup L2 from the image surface does not vary. The position of the rearlens group L2 indicated by the broken line (two-dotted) represents itsposition without an operation of the rear lens group driving motor.

In the present example, if the shortest subject distance u=700 mm, whenf=39 mm, then ΔXF(u)=1.17, and as f increases, the value of ΔXF(u) willincrease slightly, but when f=102 mm, then ΔXF(u)=1.25 and therefore theamount of increase is very little. Considering the depth of focus, it ispossible to control the movement (i.e., the movement of the lenses tothe desired position) of the lenses only by the subject distanceinformation, regardless of the focal length information from the zoomoperating device 431.

In the present example, the following relationships are given:

    XAmax=XA(f)max+ΔXF(u)max

    XBmax=XB(f)max+ΔXF(u)max

EXAMPLE 2!

FIG. 4 shows a second example of a front lens group L1 and a rear lensgroup L2.

In the present example, around the short focal length end, set by thezoom operating device 431, the following relationships are defined:

    XA=XA(f)+ΔXA(u)

XB=XB(f)+0 (i.e., regarding subject distance, the rear lens group L2should not move relative to the front lens group L1).

At other focal lengths, the following relationships are defined:

    XA=XA(f)+ΔXF(u)

    XB=XB(f)+ΔXF(u)

In the present example, if the shortest subject distance u=700 mm, whenf=39 mm, then ΔXA(u)=1.72. Regarding other focal lengths, the values ofΔXF(u) are approximately determined as follows:

when f=45 mm, then ΔXF(u)=1.17;

when f=70 mm, then ΔXF(u)=1.20;

when f=95 mm, then ΔXF(u)=1.24; and,

when f=102 mm, then ΔXF(u)=1.25.

Therefore, at focal lengths other than around the short focal lengthend, it is possible to control the position of the lenses only by thesubject distance information, regardless of the focal lengthinformation.

In the present example, the following relationships are defined:

    XAmax=XA(f)max+ΔXF(u)max

    XBmax=XB(f)max

Therefore, the relative movement of the rear lens group can beminimized. In this example, XB(f)max is less than XB(f)max in Example 1.

EXAMPLE 3!

FIG. 5 shows a third example of a front lens group L1 and a rear lensgroup L2.

In the present example, around the long focal length end, set by thezoom operating device 431, the following relationships are defined:

XA=XA(f)+0 (i.e., regarding subject distance, the front lens group L1should not move)

    XB=XB(f)+ΔXB(u)

At other focal lengths, the following relationships are defined:

    XA=XA(f)+ΔXF(u)

    XB=XB(f)+ΔXF(u)

In the present example, if the shortest subject distance u=700 mm, thevalues of ΔXF(u) are approximately determined as follows:

when f=39 mm, then ΔXF(u)=1.17;

when f=45 mm, then ΔXF(u)=1.17;

when f=70 mm, then ΔXF(u)=1.20; and,

when f=95 mm, then ΔXF(u)=1.24.

However, when f=102 mm, then ΔXB(u)=1.35.

Therefore, at focal lengths other than around the long focal length end,it is possible to control the position of the lenses only by the subjectdistance information, regardless of the focal length information.

In the present example, the following relationships are defined:

    XAmax=XA(f)max

    XBmax=XB(f)max+ΔXB(u)max

Therefore, the total movement by the whole unit driving motor isminimized.

EXAMPLE 4!

FIG. 6 shows a fourth example of a front lens group L1 and a rear lensgroup L2.

In the present example, around the short focal length end, set by thezoom operating device 431, the following relationships are defined:

    XA=XA(f)+ΔXA(u)

XB=XB(f)+0 (i.e., regarding subject distance, the rear lens group L2should not move relative to the front lens group L1)

Around the long focal length end, set by the zoom operating device 431,the following relationships are defined:

XA=XA(f)+0 (i.e., regarding subject distance, the front lens group L1should not move)

    XB=XB(f)+ΔXB(u)

And at other focal lengths, the following relationships are defined:

    XA=XA(f)+ΔXF(u)

    XB=XB(f)+ΔXF(u)

In the present example, if the shortest subject distance u=700 mm, theposition of the lenses, other than at around the short or long focallength ends, are approximately determined as follows:

when f=39 mm, then ΔXA(u)=1.72;

when f=45 mm, then ΔXF(u)=1.17;

when f=70 mm, then ΔXF(u)=1.20;

when f=95 mm, then ΔXF(u)=1.24; and,

when f=102 mm, then ΔXB(u)=1.35.

Therefore, at focal lengths other than around the short or long focallength ends, it is possible to control the position of the lenses onlyby the subject distance information, regardless of the focal lengthinformation.

In the present example, the following relationships are defined:

    XAmax=XA(f)max

    XBmax=XB(f)max

Therefore, the movement of both lens groups is minimized, as well as therelative movement of the rear lens group.

EXAMPLE 5!

FIG. 7 shows a fifth example of a front lens group L1 and a rear lensgroup L2.

In the present example, around the short focal length end, set by thezoom operating device 431, the following relationships are defined:

    XA=XA(f)+ΔXA(u)

XB=XB(f)+0 (i.e., regarding subject distance, the rear lens group L2should not move against the front lens group L1)

At other focal lengths, the following relationships are defined:

XA=XA(f)+0 (i.e., regarding subject distance, the front lens group L1should not move)

    XB=XB(f)+ΔXB(f,u)

In the present example, if the shortest subject distance u=700 mm, theposition of the lenses around the long focal length end is approximatelydetermined as follows:

when f=39 mm, then ΔXA(u)=1.72;

when f=45 mm, then ΔXF(u)=1.90;

when f=70 mm, then ΔXF(u)=1.42;

when f=95 mm, then ΔXF(u)=1.35; and,

when f=102 mm, then ΔXB(u)=1.35.

Therefore, at the short focal length end, it is possible to control theposition of the lenses only by the subject distance information, and atother focal lengths it is possible to control the position of the lensesby the focal length information and the subject distance information. Inthe present example, the following relationships are defined:

    XAmax=XA(f)max

    XBmax=XB(f)max

Therefore, the movement of both lens groups is minimized, as well as therelative movement of the rear lens group. The position of the lenses,however, may differ according to the focal length.

The mechanical structure of the zoom lens shown in FIG. 1 illustrates asimple example thereof. Various mechanical structures may actually bemade, and thus the present description shall not refer to the mechanicalstructure itself.

As above described, according to the method of focusing the zoom lenscamera in the present embodiment, when the focus operating device isoperated, focusing is performed in such a manner that, the whole unitdriving motor which drives the front and the rear lens group as a whole,and the rear lens group driving motor which varies the distance betweenthe front lens group and the rear lens group, move together, and therebyflexible control of the lens position will be facilitated.

To realize the zoom lens and the method of lens driving shown in FIGS. 2through 7, several embodiments will now be described with reference toFIGS. 8 to 23.

The following embodiments are applied to a lens shutter type of zoomlens camera, as shown in FIG. 26. The concept of the present zoom lenscamera will now be described with reference to FIG. 20.

FIG. 20 shows a zoom lens barrel 10, provided in the present zoom lenscamera, of a three-stage delivery type having three moving barrels,namely a first moving barrel 20, a second moving barrel 19 and a thirdmoving barrel 16. Two lens groups are provided, namely a front lensgroup L1 having positive power and a rear lens group L2 having negativepower.

In the main body of the camera, a whole unit driving motor controllingcircuit 60, a rear lens group driving motor controlling circuit 61, azoom operating device 62, a focus operating device 63, an objectdistance measuring apparatus 64, a photometering apparatus 65, an AE(i.e., automatic exposure) motor controlling circuit 66, and a CPU(i.e., central processing unit) 210, are provided. The CPU 210 controlsthe above devices, circuits and apparatuses. Although the specificobject distance measuring apparatus 64 which is used to provideinformation regarding the object-to-camera distance does not form partof the present invention, one such suitable system is disclosed incommonly assigned U.S. patent application Ser. No. 08/605,759, filed onFeb. 22, 1996, the entire disclosure of which is expressly incorporatedby reference herein. Although the systems disclosed in such applicationare of the so-called "passive" type, other known autofocus systems(e.g., active range finding systems such as those based on infraredlight and triangulation) may be used. Similarly, a photometering systemas disclosed in the noted U.S. patent application Ser. No. 08/605,579could be implemented as photometering system 65.

When the zoom operating device 62, for example in the form of a zoomlever provided on the camera body (i.e., a "wide" zoom button 62WB and a"tele" zoom button 62TB, as shown in FIG. 28), is operated, the CPU 210outputs commands to the whole unit driving motor controlling circuit 60to move the front lens group L1 and the rear lens group L2, rearwardlyor forwardly without consideration of the focal length and a focal pointthereof.

In the following explanation, forward and rearward movements of thelenses L1 and L2 by the whole unit driving motor control circuit 60 (themotor 25) are referred to as the movement toward "tele" and the movementtoward "wide", respectively, since forward and rearward movements of thelenses L1 and L2 occur when the zoom operating device 62 is operated to"tele" and "wide" positions.

The image magnification of the visual field of the finder 427 (FIG. 1),varies sequentially to the variation of the focal length through theoperation of the zoom operating device 62. Therefore, the photographermay perceive the variation of the set focal length through the operationof the zoom operating device 62, by observing the variation of imagemagnification of the visual field of the finder. In addition, the focallength, set by the operation of the zoom operating device 62, may beperceived by a value indicated on an LCD (i.e., liquid crystal display)panel 224, as shown in FIG. 28.

When the focus operating device 63 is operated, the CPU 210 drives thewhole unit driving motor 25 driven via the whole unit driving motorcontrolling circuit 60, and additionally drives a rear lens groupdriving motor 30 driven via the rear lens group driving motorcontrolling circuit 61, so that the front and rear lens groups L1 and L2are moved to a position corresponding to a set focal length and adetected object distance, and whereby the zoom lens is focused on thesubject.

Specifically, the focus operating device 63 is provided with a releasebutton 217B. A photometering switch SWS and a release switch SWB aresynchronized with the release button 217B. When the release button 217Bis half-depressed (half step), through the CPU 210, the photometeringswitch SWS is made ON, and the respective object distance measuring andphotometering commands are input to the object distance measuringapparatus 64 and the photometering apparatus 65.

When the release button 217B is fully depressed (full step), the CPU 210causes the release switch SWR to be made ON, and according to the resultof the object distance measuring device and a set focal length, thewhole unit driving motor 25 and the rear lens group driving motor 30 aredriven, and the focusing process, in which the front lens group L1 andthe rear lens group L2 move to the focusing position, is executed.Further, an AE motor 29 of an AF/AE (i.e., autofocus/autoexposure)shutter unit 21 (FIG. 21) is driven via the AE motor controlling circuit66, and a shutter 27 is actuated. During the shutter action, upon theinput of the photometering information output from the photometeringapparatus 65, the CPU 210 drives the AE motor 29 and opens shutterblades 27a of the shutter 27 for a specified period of time. In the zoomlens camera of the present embodiment, immediately after the shutterblades 27a are closed, by driving the rear lens group driving motor 30,the rear lens group L2 moves forwardly to the initial position thereof.The focus operating device 63, though not shown, includes a switchingmechanism to execute the focusing process by the CPU 210.

When the zoom operating device 62 is operated, the CPU 210 drives thewhole unit driving motor 25, and the front lens group L1 and the rearlens group L2 move together as a whole in the optical axis direction.Simultaneous with such a movement, the rear lens group driving motor 30may also be driven via the rear lens group driving motor controllingcircuit 61. However, this is not performed under the conventionalconcept of zooming in which the focal length is varied sequentiallywithout moving the position of the focal point.

Motors 29 and 30 are identical, and comprise DC motors having a minimumtorque of 1.5 gram*cm at a rated voltage (i.e., 1.5V); motor 25comprises a DC motor which has a minimum torque of 12.0 gram*cm. at arated voltage (i.e., 2.4V). One example of motors 29 and 30 are motorsmanufactured by Sanyo Seimitsu Co., Ltd. of Japan, under motor code No.M-01166600; and an example of motor 25 is a motor which is alsomanufactured by Sanyo Seimitsu Co., Ltd. of Japan, under motor code No.M-01154200.

An example of the embodiment of the zoom lens barrel according to theabove concept will now be described with reference to FIGS. 18 and 19.

The overall structure of the zoom lens barrel 10 in the presentembodiment will firstly be described.

The zoom lens barrel 10 is provided with the first moving barrel 20, thesecond moving barrel 19, the third moving barrel 16, and a fixed lensbarrel block 12. The third moving barrel 16 is engaged with acylindrical part of the fixed lens barrel block 12, and moves in theoptical axis direction upon being rotated. The third moving barrel 16 isprovided on an inner periphery thereof with a linear guide barrel 17,which is restricted in rotation. The linear guide barrel 17 and thethird moving barrel 16 move together as a whole in the optical axisdirection, with the third moving barrel 16 rotating relative to thelinear guide barrel 17. The first moving barrel 20 moves in the opticalaxis direction with rotation thereof being restricted. The second movingbarrel 19 moves in the optical axis direction, while rotating relativeto the linear guide barrel 17 and the first moving barrel 20. The wholeunit driving motor 25 is secured to the fixed lens barrel block 12. Ashutter mounting stage 40, on which the AE motor 29 and the rear lensgroup driving motor 30 are mounted, is secured to the first movingbarrel 20. The front lens group L1 and the rear lens group L2 arerespectively supported by a lens supporting barrel 34 and a lenssupporting barrel 50.

On the inner periphery of the fixed lens barrel block 12, a femalehelicoid 12a, and a plurality of linear guide grooves 12b formedparallel to an optical axis O, are provided. An aperture plate 14 havingan aperture 14a which defines a portion of the film to be exposed, isprovided, as shown in FIG. 18.

In the fixed lens barrel block 12, a gear housing 12c, expanding in theradial direction, and extending in the optical axis direction, isprovided as shown in FIG. 14. In the gear housing 12c, a driving pinion15, extending in the optical axis direction, is rotatably held. The endsof a shaft 7 of the driving pinion 15 are rotatably supported, by asupporting hollow 4 provided in the fixed lens barrel block 12, and by asupporting hollow 31a provided on a gear supporting plate 31,respectively. The teeth of the driving pinion 15 project into the innerperiphery of the fixed lens barrel block 12.

At the bottom part of one of the linear guide grooves 12b, namely 12b',the code plate 13a having a predetermined pattern is fixed, as shown inFIG. 14. The linear guide groove 12b' is provided so that it may bepositioned at an approximate diagonal position of the photographingplane in regard to the fixed lens barrel block 12. The code plate 13a isprovided along substantially the whole of the length of the fixed lensbarrel block 12 (i.e., in the optical axis direction). The code plate13a is part of a flexible printed circuit board 13 positioned outsidethe fixed lens barrel block 12. On the flexible printed circuit board13, a photointerrupter 1 is secured, which in combination with arotating plate 2 comprises an encoder for detecting a rotation of thewhole unit driving motor 25. The rotating plate 2 is fixed on a shaft ofthe whole unit driving motor 25 as shown in FIG. 19.

On an inner periphery of the third moving barrel 16, a plurality oflinear guide grooves 16c, formed parallel to the optical axis, areprovided. At an outer periphery of the rear end of the third movingbarrel 16, a male helicoid 16a, which engages with the female helicoid12a of the fixed lens barrel block 12, and an outer peripheral gear 16b,which engages with the driving pinion 15, are provided as shown in FIG.13. The driving pinion 15 has an axial length sufficient to be capableof engaging with the outer peripheral gear 16b throughout the entirerange of movement of the third moving barrel 16 in the optical axisdirection.

The linear guide barrel 17 is provided, on a rear part of an outerperiphery thereof, with a rear end flange 17d. The rear end flange 17dhas a plurality of engaging projections 17c projecting away from theoptical axis in the radial direction. An anti-dropping flange 17e isprovided just in front of the rear end flange 17d. The anti-droppingflange 17e has a radius smaller than the rear end flange 17d. In thecircumferential direction of the anti-dropping flange 17e, a pluralityof notches 17f are formed. On an inner periphery of the rear end of thethird moving barrel 16, a plurality of engaging projections 16d,projecting towards the optical axis in a radial direction are provided,as shown in FIG. 18. By inserting the engaging projections 16d into thenotches 17f, the engaging projections 16d are positioned between theflanges 17d and 17e, and by the relative rotation of the linear guidebarrel 17, the engaging projections 16d are engaged with the linearguide barrel 17. On the rear end surface of the linear guide barrel 17,an aperture plate 23 having an aperture 23a approximately the same shapeas the aperture 14a, is fixed.

The relative rotation of the linear guide barrel 17, with respect to thefixed lens barrel block 12, is restricted by the slidable engagement ofthe plurality of engaging projections 17c with the corresponding linearguide grooves 12b, formed parallel to the optical axis O. One of theengaging projections 17c, namely 17c' (a linear guide key), is fixed toa contact terminal, i.e., a brush 9, which is in slidable contact withthe code plate 13a, fixed to the bottom of the linear guide groove 12b',to generate signals corresponding to focal length information duringzooming. The engaging projection 17c' is positioned approximatelydiagonal to the photographing plane.

The contacting terminal 9 is provided with a pair of brushes (electricarmatures) 9a, which are approximately perpendicular to a fixing part 9band in slidable contact with the code plate 13a, and a pair ofpositioning holes 9d (see FIG. 103). The pair of brushes 9a areelectrically continuous with each other via the fixing part 9b.

As illustrated in FIG. 30, on the code plate 13a, four types ofelectrode patterns ZC0, ZC1, ZC2 and ZC3 are provided aligned in adirection perpendicular to the longitudinal direction of the code plate13a. The electrode patterns ZC0, ZC1, ZC2 and ZC3 form a predeterminedpattern in combination, so that a predetermined signal (i.e., voltage)may be output, when the pair of brushes 9a slide along the longitudinaldirection of the code plate 13a, conducting through the electrodepatterns ZC0, ZC1, ZC2 and ZC3 designated in advance corresponding tothe slide position.

On the inner periphery of the linear guide barrel 17 a plurality oflinear guide grooves 17a are formed parallel to the optical axis O. Aplurality of lead grooves 17b are formed on the linear guide barrel 17to extend through, and pass through, the peripheral wall of the linearguide barrel 17. The lead grooves 17b are formed oblique (inclined) tothe optical axis.

The second moving barrel 19 engages with the inner periphery of thelinear guide barrel 17. On the inner periphery of the second movingbarrel 19, a plurality of lead grooves 19c are provided in a directioninclined oppositely to the lead grooves 17b. On the outer periphery ofthe rear end of the second moving barrel 19 a plurality of followerprojections 19a, having a trapezoidal cross-sectional shape projectingaway from the optical axis in a radial direction, are provided. Followerpins 18 are positioned in the follower projections 19a. Each followerpin 18 consists of a ring member 18a, and a center fixing screw 18bwhich supports the ring member 18a in the follower projection 19a. Thefollower projections 19a are in slidable engagement with the leadgrooves 17b of the linear guide barrel 17, and the follower pins 18 arein slidable engagement with the linear guide grooves 16c of the thirdmoving barrel 16. With such an arrangement, when the third moving barrel16 rotates, the second moving barrel 19 moves linearly in the opticalaxis direction, while rotating.

On the inner periphery of the second moving barrel 19, the first movingbarrel 20 is engaged. In the first moving barrel 20, a plurality offollower pins 24, provided on an outer periphery of the rear thereof,are engaged with the corresponding inner lead grooves 19c, and at thesame time the first moving barrel 20 is guided linearly by a linearguide member 22. As shown in FIGS. 8 and 9, the linear guide member 22is provided with an annular member 22a, a pair of guide legs 22b, whichproject from the annular member 22a in the optical axis direction, and aplurality of engaging projections 28 which project from the annularmember 22a away from the optical axis in a radial direction. Theengaging projections 28 slidably engage with the linear guide grooves17a. The guide legs 22b are inserted between the inner peripheral faceof the first moving barrel 20 and the AF/AE shutter unit 21.

The annular member 22a of the linear guide member 22 is connected to therear of the second moving barrel 19, such that the linear guide member22 and the second moving barrel are capable of moving along the opticalaxis direction as a whole, and in addition are capable of relativerotation around the optical axis. On the outer periphery of the rear ofthe linear guide member 22 a rear end flange 22d is provided having aplurality of engaging projections 28b which project away from theoptical axis in the radial direction. In front of the rear end flange22d there is provided an anti-dropping flange 22c, having a radiussmaller than the rear end flange 22d. Along the circumferentialdirection of the anti-dropping flange 22c, a plurality of notches 22eare formed, as shown in FIG. 8. On the inner periphery of the rear ofthe second moving barrel 19, a plurality of engaging projections 19b,projecting towards the optical axis in a radial direction, are providedas shown in FIG. 18, and by inserting the engaging projections 19b intothe notches 22e, the engaging projections 19b are positioned between theflanges 22c and 22d, and by relative rotation of the linear guide member22, they are engaged with the linear guide member 22. With the abovestructure, when the second moving barrel 19 rotates clockwise orcounterclockwise, the first moving barrel 20 moves linearly, forwardlyand rearwardly in the optical axis direction, but is restricted fromrotating.

At the front of the first moving barrel 20, a barrier apparatus 35having barrier blades 48a and 48b is mounted, and on an inner peripheralface of the first moving barrel 20 the AF/AE shutter unit 21 having theshutter 27, consisting of three shutter blades 27a, is engaged and fixedas shown in FIG. 12. The AF/AE shutter unit 21 is provided with aplurality of fixing hollows 40a formed at even angular intervals on theouter periphery of the shutter mounting stage 40 as shown in FIG. 10.The plurality of follower pins 24 serve to fix the AF/AE shutter unit21. The follower pins 24 are inserted and fixed in hollows 20a, formedon the first moving barrel 20, and in the fixing hollows 40a. With thisarrangement the shutter unit 21 is secured to the first moving barrel 20as shown in FIG. 11. The follower pins 24 may be fixed by an adhesive orby screws for example. For reference, numeral 41 is a decorative platesecured to the front of the first moving barrel 20.

As illustrated in FIGS. 12 and 19, the AF/AE shutter unit 21 is providedwith the shutter mounting stage 40, a shutter blade supporting ring 46fixed on the rear of the shutter mounting stage 40, and the lenssupporting barrel 50 (i.e., for the rear lens group L2) supported in astate of being capable of movement relative to the shutter mountingstage 40. On the shutter mounting stage 40, the front lens group L1, theAE motor 29, and the rear lens group driving motor 30, are supported.The shutter mounting stage 40 is provided, with an annular member 40fhaving a photographing aperture 40d. The shutter mounting stage 40 isalso provided with three legs 40b which project rearwards from theannular member 40f. Three slits are defined between the three legs 40b,and two of the slits comprise linear guides 40c, which slidably engagewith the respective pair of guide legs 22b of the linear guide member22, so as to guide the movement of the linear guide member 22.

The shutter mounting stage 40 supports an AE gear train 45, whichtransmits rotation of the AE motor 29 to the shutter 27, a lens drivinggear train 42, which transmits rotation of the rear lens group drivingmotor 30 to a screw shaft 43, photointerrupters 56 and 57, connected tothe flexible printed circuit board 6, and rotating plates 58 and 59,having a plurality of radially formed slits provided in thecircumferential direction. An encoder for detecting a rotation of therear lens group driving motor 30 consists of the photointerrupter 56 andthe rotating plate 58, and an encoder for detecting a rotation of the AEmotor 29 consists of the photointerrupter 57 and the rotating plate 59.

The shutter 27, a supporting member 47 which pivotally supports thethree shutter blades 27a of the shutter 27, and a circular drivingmember 49, which gives rotative power to the shutter blades 27a, arepositioned between the shutter mounting stage 40 and a shutter bladesupporting ring 46, secured to the shutter mounting stage 40. Thecircular driving member 49 is provided with three operating projections49a at even angular intervals, which respectively engage with each ofthe three shutter blades 27a. As shown in FIG. 12, the shutter bladesupporting ring 46 is provided, at a front end thereof, with aphotographing aperture 46a and with three supporting hollows 46bpositioned at even angular intervals around the photographing aperture46a. On an outer periphery of the shutter blade supporting ring 46 thereis provided a deflection restricting member 46c, which is exposed fromthe linear guides 40c and which slidable supports the inner peripheralfaces of the pair of guide legs 22b.

The supporting member 47 positioned in front of the shutter bladesupporting ring 46 is provided with a photographing aperture 47a,aligned with the photographing aperture 46a, and with three shafts 47b(only one of which is illustrated in FIG. 12) at respective positionsopposite the three supporting hollows 46b. Each of the three shutterblades 27a are respectively provided with a shaft hole 27b into whichone end of each respective shaft 47b is inserted, with a blocking part(not shown) which prevents unwanted light from entering thephotographing apertures 46a and 47a at the other end, and with a slot27c, through which the operating projection 49a is inserted, between theone end and the other end thereof. The supporting member 47 is fixed tothe shutter blade supporting ring 46 in such a manner that, each shaft47b which supports a corresponding shutter blade 27a, is engaged with acorresponding supporting hollow 46b of the shutter blade supporting ring46.

On the outer periphery of the circular driving member 49, gears 49b areprovided to receive the rotation from the gear train 45. The supportingmember 47 is provided, at the position close to the three shafts 47b,with three arc grooves 47c, which are arched in the circumferentialdirection. The three operating projections 49a of the circular drivingring 49 engage with the slots 27c of the respective shutter blades 27athrough the three arc grooves 47c. The shutter blade supporting ring 46is inserted from the rear of the shutter mounting stage 40, to supportthe circular driving ring 49, the supporting member 47 and the shutter27, and is fixed on the shutter mounting stage 40 by screws.

At the rear of the shutter blade supporting ring 46, the lens supportingbarrel 50, supported to be able to move relative with respect to theshutter mounting stage 40 via slide shafts 50 and 51, is positioned. Theshutter mounting stage 40 and the lens supporting barrel 50 are urged tomove, by a coil spring 3 fitted to the slide shaft 51, in oppositedirections away from each other, and therefore play between the two isreduced. In addition, a driving gear 42a provided at the gear train 42is restricted to move in the axial direction, and on the inner peripherythereof, an internal thread (not shown) is formed. The screw shaft 43,one end of which is fixed to the lens supporting barrel 50, engages withthe internal thread, and a feed screw structure is provided consistingof the driving gear 42a and the screw shaft 43. In such a manner, whenthe driving gear 42a rotates clockwise or counterclockwise due todriving by the rear lens group driving motor 30, the screw shaft 43respectively moves forwardly or rearwardly with respect to the drivinggear 42a and the lens supporting barrel 50, namely, the rear lens groupL2 supported by the lens supporting barrel 50, moves relative to thefront lens group L1.

At the front of the shutter mounting stage 40, pressers 53 and 55, whichpress against respective motors 29 and 30, are screwed to the shuttermounting stage 40. The motors 29, 30 and the photointerrupters 56, 57are connected to the flexible printed circuit board 6. One end of theflexible printed circuit board 6 is fixed to the shutter mounting stage40. When the first, second and third moving barrels 20, 19 and 16, andthe AF/AE shutter unit 21 and the like are assembled, the aperture plate23 is fixed to the rear of the linear guide barrel 17. At the front ofthe fixed lens barrel block 12, an anti-dropping member 33, having acircular shape, is engaged.

At the front of the first moving barrel 20 positioned at the front mostpart of the zoom lens barrel 10, the barrier apparatus 35, having pairsof barrier blades 48a and 48b, serving respectively as follower barrierblades and main barrier blades, are provided. Towards the rear of thedecorative plate 41, an annular plate 96 is fixed, and between thedecorative plate 41 and the annular plate 96, the barrier blades 48a and48b are connectively engaged. In addition, at the front of the firstmoving barrel 20, between a front surface 20b and the annular plate 96,a barrier driving ring 96, having a pair of barrier driving levers 98aand 98b, is rotatably provided. The barrier driving ring 97, is rotatedclockwise or counterclockwise, by a barrier interlocking gear 92 whichdrives rotatably upon receiving a rotation of the rear lens groupdriving motor 30, and via the barrier driving levers 98a and 98b opensor closes the main barrier blades 48b together with the follower barrierblades 48a.

While in the above description of the present embodiment, the zoom lensconsisted of two groups, namely the front lens group L1 and the rearlens group L2, it should be understood that the structure is not limitedto the present embodiment disclosed above. In addition, in the aboveembodiment, the front lens group L1, and the rear lens group L2,supported by the lens supporting barrel 50, are provided as componentsof the AF/AE shutter unit 21, and the rear lens group driving motor 30is mounted to the shutter unit 21. With such a structure, although thesupporting structure and the driving structure of the rear lens group L2are simplified, the present zoom lens may also be realized in such amanner by making the rear lens group L2 a member apart from the AF/AEshutter unit 21, which is provided with the shutter mounting stage 40,the circular driving member 49, the supporting member 47, the shutterblades 27, the shutter blade supporting ring 46 and the like, and thatthe rear lens group L2 is supported by any supporting member other thanthe shutter unit 21.

In the zoom lens camera of the present embodiment, the operation byrotation of the whole unit driving motor 25 and the rear lens groupdriving motor 30 will now be described.

As shown in FIG. 16, when the zoom lens barrel 10 is at the mostretracted (withdrawn) position, i.e., the lens-housed condition, whenthe power switch is turned ON, the whole unit driving motor 25 rotatesby a small amount in the forward (clockwise) direction. This rotation istransmitted, via a gear train 26, supported by a supporting member 32,to the driving pinion 15, and since the third moving barrel 16 isrotated in the optical axis direction (i.e., is extended), the secondmoving barrel 19 and the first moving barrel 20 are extended by a smallamount in the optical axis direction, along with the third moving barrel16, and therefore the camera is in a state capable of photographing,with the zoom lens positioned at the widest position, i.e., the wideend. At this time, due to the fact that the amount of movement of thelinear guide barrel 17, with respect to the fixed lens barrel block 12,is detected through the relative slide between the code plate 13a andthe contacting terminal 9, the focal length of the zoom lens, i.e., thefront and rear lens group L1 and L2, is detected.

In the photographable state as above described, when the zoom "tele"switch is made ON, the whole unit driving motor 25 drives forward(clockwise), and rotates the third moving barrel 16 in the direction inwhich it is extended via the driving pinion 15 and the outer peripheralgear 16b. Therefore, the third moving barrel 16 is extended from thefixed lens barrel block 12, according to the relationship between thefemale helicoid 12a and the male helicoid 16a, and at the same time, thelinear guide barrel 17, without relative rotation to the fixed lensbarrel block 12, according to the relationship between the engagingprojections 17c and the linear guide grooves 12b, moves forwardly in theoptical axis direction together with the third moving barrel 16. At thistime, the simultaneous engagement of the follower pins 18 with the leadgroove 17b and the linear guide groove 16c causes the second movingbarrel 19 to move forward relative to the third moving barrel 16 in theoptical axis direction, while rotating relative to and in the samedirection as the third moving barrel 16. The first moving barrel 20,because of the state of being guided linearly by the linear guide member22 and also of the state that movement of the follower pins 24 areguided by the lead grooves 19c, moves forwardly in the optical axisdirection together with the AF/AE shutter unit 21, from the secondmoving barrel 19, without relative rotation to the fixed lens barrelblock 12. During such movements, according to the fact that the movingposition of the linear guide barrel 17 with respect to the fixed lensbarrel block 12 is detected through the relative slide between the codeplate 13a and the contacting terminal 9, the focal length set by thezoom operating device 62, is detected.

When the zoom "wide" switch is made ON, the whole unit driving motor 25drives in reverse (counterclockwise), and the third moving barrel 16 isrotated in the direction in which it is retracted and is retracted intothe fixed lens barrel block 12 together with the linear guide barrel 17.At the same time, the second moving barrel 19 is retracted into thethird moving barrel 16, while rotating in the same direction as that ofthe third moving barrel 16, and the first moving barrel 20 is retractedinto the rotating second moving barrel 19 together with the AF/AEshutter unit 21. During the above retraction driving, like the case ofextending driving as above described, the rear lens group driving motor30 is not driven.

While the zoom lens 10 is driven during the zooming operation, since therear lens group driving motor 30 is not driven, the front lens group L1and the rear lens group L2 move as a whole, maintaining a constantdistance between each other, as shown in FIG. 15. The focal lengthinputted via the zoom code plate 13a is indicated on the LCD panel 224.

At any focal length set by the zoom operating device 62, when therelease button 217B is depressed by a half-step, the CPU 210 obtainsfocusing information from the object distance measuring apparatus 64 andphotometering information from the photometering apparatus 65. In such astate, when the release button 217B is fully depressed, CPU 210 movesthe whole unit driving motor 25 and the rear lens group driving motor 30by an amount corresponding to the focal length information set inadvance and by the subject distance information from the object distancemeasuring apparatus 64, to the specified focal length, and brings thesubject into focus. Further, via the AE motor controlling circuit 66,the AE motor 29 drives the circular driving member 49 according tosubject luminance information obtained from the photometering apparatus65, and drives the shutter 27 in order to satisfy the required exposure.After such a shutter release, the whole unit driving motor 25 and therear lens group driving motor 30 are both driven immediately, and thefront lens group L1 and the rear lens group L2 are moved to the positionprior to shutter release.

When a power switch 212 is made OFF and the electric power is cut, thezoom lens 10 is retracted to the lens housed position as shown in FIG.18 by the whole unit driving motor 25. Before such a withdrawalmovement, the whole unit driving motor 25 is driven, and the rear lensgroup L2 moves to the home position.

In regard to the movement control of the front lens group L1 and therear lens group L2 performed when the release button 217B is fullydepressed, the rear lens group driving motor 30 moves the rear lensgroup L2 rearwardly away from the front lens group L1, by an amountcorresponding to the subject distance information obtained from theobject distance measuring apparatus 64 and the focal length informationset by the zoom operating device 31. At the same time, the whole unitdriving motor 25 moves the front lens group L1 by an amountcorresponding to the subject distance information obtained from theobject distance measuring apparatus 64 and the focal length informationset by the zoom operating device 31. Due to the movement of the frontlens group L1 and the rear lens group L2, the focal length is set andsubject focusing is performed. After completion of the shutter release,the rear lens group driving motor 30 and the whole unit driving motor 25are driven immediately, so that both lens groups L1 and L2 are returnedto the position they were at prior to the shutter release.

When the zoom operating device 62 is operated to the "wide" position,the whole unit driving motor 25 drives in reverse (counterclockwise),and the third moving barrel 16 is rotated in the retraction direction,and is retracted into a cylinder 11 of the fixed lens barrel block 12,together with the linear guide barrel 17. At the same time, the secondmoving barrel 19 is retracted into the third moving barrel 16, with arotation similar to that of the third moving barrel 16, and the firstmoving barrel 20 is retracted into the rotating second moving barrel 19together with the AF/AE shutter unit 21. During the above retractiondriving, likewise the case of extension driving as above mentioned, therear lens group driving motor 30 is not driven. When the power switch isOFF, the zoom lens 10 is retracted to the housed position as shown inFIG. 18, by driving the whole unit driving motor 25 accordingly.

A detailed description in regard to lens drive control, which is one ofthe characteristics of the zoom lens barrel of the zoom lens camera ofthe present embodiment, will now be described with reference to FIGS. 24and 25.

FIG. 24 illustrates the loci of the movements of the front lens group L1and the rear lens group L2, and FIG. 25 illustrates the range ofmovement of the rear lens group L2 compared to the front lens group L1.

In FIG. 24, line A represents the locus of the front lens group L1, lineB represents the locus of the rear lens group L2 before the releasebutton is fully depressed, and line C represents the locus of the rearlens group L2 when the release button is fully depressed. As can beunderstood from FIG. 24, during focusing, the distance between the frontlens group L1 and the rear lens group L2 is wider at the "wide" end(i.e., "W" end) position, and is shorter at the "tele" end (i.e., "T"end) position.

Before and during an operation of the zoom operating device 62, the rearlens group L2 is positioned at the standby position as shown in FIG. 25,and the constant distance to the front lens group L1 is maintained. Whenthe release button is fully depressed, the rear lens group L2 movesrearwardly, namely to the right in FIG. 25, and moves to thephotographing position and focusing is performed. When the rear lensgroup L2 moves rearwardly, the initial position (i.e., the referenceposition) of the rear lens group L2 (i.e., the rear lens supportingbarrel 50) is detected via a photo sensor (not shown), and from theinitial moment of position detecting, pulse counting is commenced. Whenthe pulse counting reaches a value corresponding to an amount ofmovement, corresponding to the subject distance information obtainedfrom the object distance measuring apparatus 64 and the focal lengthinformation set by the zoom operating device 62, the rear lens groupdriving motor 30 is stopped.

In FIG. 25, the range indicated as "Adjusting Range", equals the rangecorresponding to the minimum value of the pulse counting from theinitial position, when the zoom lens barrel 10 is positioned at the"tele" end and at the same time the focused subject is at infinity.Therefore, the rear lens group L2 is moved rearwardly with respect tothe front lens group L1, by an amount, such as the adjusting quantity,from the initial position.

FIG. 21 illustrates the state when the zoom lens barrel 10 is around the"wide" end position, before the release button has been fully depressed,while FIG. 22 illustrates the state when the zoom lens barrel 10 isaround the "wide" end position, immediately after the release button hasbeen fully depressed. As above described, from the state as shown inFIG. 22, after the shutter release is complete, the rear lens groupdriving motor 30 drives immediately and the rear lens group L2 movestowards the front lens group L1, and returns to the state as shown inFIG. 21.

After completion of the shutter release from the state as shown in FIG.22, if the rear lens group driving motor 30 is not immediately driven,and therefore the rear lens group L2 remains in the photographingposition as shown in FIG. 22, if a serious external force or impact ismade towards the front of the first moving barrel 20, in a directiontowards the main body of the camera, namely to the right in FIG. 22, allthe moving barrels, namely, the first moving barrel 20, the secondmoving barrel 19 and the third moving barrel 16, will be forced to bewithdrawn into the main body of the camera, and in such a case, the rearlens group L2 may collide with a film F. Therefore, there may be apossibility that not only the film F or the rear lens group L2, but alsoother apparatus or devices may be damaged. Such a state is illustratedin FIG. 23.

However, according to the lens drive control of the zoom lens barrelprovided in the camera of the present embodiment, after completion ofthe shutter release from the state as shown in FIG. 22, the rear lensgroup driving motor 30 is immediately driven and the rear lens group L2is moved towards the front lens group L1 and is returned to the positionas shown in FIG. 21. Thus, the above problem is unlikely to occur.

The above embodiment refers to a three-stage delivery zoom lens barrel,however, it should be understood that the structure is not limited tosuch a lens barrel, and can be equally applied to a one-stage, two-stageor more than three-stage delivery zoom lens barrel.

As above described, in accordance with the lens driving method of thezoom lens and the zoom lens barrel in the present embodiment, during thezoom operation, the front lens group and the rear lens group move as awhole without varying the distance between the two lens groups, andduring the release operation, the rear lens group moves rearwardly withrespect to the front lens group, and after completion of release, therear lens group moves towards the front lens group, so that both lensgroups are returned to the initial position that they were at during thezoom operation. Therefore, in a state that the lens barrel is extendedfrom the main body of the camera, if a serious external force or impactis made to the front of the lens barrel in a direction towards the mainbody of the camera, and the lens barrel is forced to be retractedaccordingly, it is unlikely that the rear lens group might collide withthe film, and therefore the film, the rear lens group or the lensdriving apparatus will not be damaged.

FIGS. 26 through 28 respectively illustrate a front elevational view, arear elevational view and a plan view of the lens shutter type camera ofthe present embodiment, provided with the zoom lens barrel as shown inFIGS. 1 through 25.

At approximately a center of the front of a camera body 201, the zoomlens barrel 12 is mounted. On the front surface of the camera body 201,a light receiving element 65a for photometering, an AF sensor window64a, a finder window 207a of a finder optical system, a stroboscopiclamp 209, and a self-timer indicating lamp 229, are all provided. At thebottom of the camera body 201, a battery cover 202 is provided.

On the rear surface of the camera body 201, a rear cover 203, openingand closing for the purpose of loading or removing a film cartridge, arear cover opening lever 204, used to unlock the locking device to openthe rear cover 203, a green lamp 228, which indicates the result offocusing, a red lamp 227, which indicates the state of strobe charging,an eyepiece 207b, and a power (ON/OFF) button 212B, are provided.

On the top surface of the camera body 201, as viewed from the left ofthe drawing, a rewind button 216B, the LCD panel 224, a mode button214B, a driving button 215B, the release button 217B, the "wide" button62WB, and the "tele" button 62TB, are provided.

FIG. 29 illustrates a structure of the main internal components of thezoom lens camera of the present embodiment. The camera is provided withthe CPU 210 that controls the overall functions of the camera.

The CPU 210 drives and controls the whole unit driving motor 25, via thewhole unit driving motor controlling circuit 60, the rear lens groupdriving motor 30, via the rear lens group driving motor controllingcircuit 61, and the AE motor 29, via the AE motor controlling circuit66. The CPU 210 also controls, via a film feeding control circuit 225, afilm feeding motor 226 which performs loading, winding and rewinding offilm. The CPU 210 further controls flashing of a strobe (i.e., anelectronic flash) via a strobe device 231.

The CPU 210 is capable of operation when a battery 211 is loaded, andexecutes the functions according to the i/o state (i.e., ON/OFF) of eachswitch, namely the state of the power switch 212, a rear cover switch213, a mode switch 214, a driving switch 215, a "tele" switch 62T, a"wide" switch 62W, a rewind switch 216, the photometering switch SWS,and the release switch SWR.

The power switch 212 is connected to the power button 212B, and when thepower switch 212 is "ON" when the electric power is "OFF" (i.e., theelectric power of the battery 211 is cut), the power switch 212 turnsthe electric power "ON" (i.e., the electric power of the battery 211 issupplied), and when the power switch 212 is "OFF" when the electricpower is "ON", the power switch 212 turns the electric power "OFF".

The rear cover switch 213 is connected to the opening or closing of therear cover 203, and according to variations in the state of the rearcover 203, the rear cover switch 213 executes film loading processing bydriving the film feeding motor 226, or makes a film counter reset.

The mode switch 214 is used to change photographing modes, and isconnected to the mode button 214B. Every time the mode switch 214 is"ON", photographing modes are changed, such as an auto strobe flashingmode, a forced strobe flashing mode, a strobe flashing forbidding mode,a long exposure mode, or a bulb mode etc.

The driving switch 215 changes between various driving modes, and isconnected to the driving button 215B. Every time the driving switch 215is "ON", driving modes are changed, such as a frame photographing mode,a self-timer mode, a continuous photographing mode, or a multipleexposure mode etc.

The "tele" switch 62T is connected to the "tele" button 62TB. When the"tele" switch 62T is "ON", the whole unit driving motor 25 drives towardthe "tele" end.

The "wide" switch 62W is connected to the "wide" button 62WB. When the"wide" switch 62W is "ON", the whole unit driving motor 25 drives towardthe "wide" end.

The photometering switch SWS and the release switch SWR are connected tothe release button 217B. When the release button 217B is half depressed,the photometering switch SWS is made "ON", and when the release button217B is fully depressed, the release switch SWR is made "ON". During thetime that the release button 217B is between being half depressed andbeing fully depressed, the photometering switch SWS is maintained in the"ON" state. When the photometering switch SWS is "ON", photometering andobject distance measuring are executed. When the release switch SWR is"ON", and according to the result of the object distance measurement,the whole unit driving motor 25 and the rear lens group driving motor 30are driven so that the front lens group L1 and the rear lens group L2may be moved to a position at which the subject is brought into focus,and the AE motor 29 is driven and the exposure processing is executedaccording to the photometer value. After exposure is complete, the wholeunit driving motor 25 and the rear lens group driving motor 30 drive,and the front lens group L1 and the rear lens group L2 return to thepositions they were at before such a movement. The film feeding motor226 is driven and the film is wound by one frame.

The CPU 210 inputs an output from a DX-code information input circuit218, which reads information regarding the ISO speed of film, a zoomcode information input circuit 219, which reads information regardingthe present lens position from the code plate 13a, a zoom pulse inputcircuit 220, an AE pulse input circuit 221, an AF pulse input circuit222, a wind pulse input circuit 223, which detects driving of the filmand the amount of driving thereof, and an AF home position detectingcircuit 232, are input.

A number of indicators, namely, the LCD panel 224, which indicates acurrent focal length, the number of frames photographed, the exposuremode or the like, the red lamp 227, which indicates the state of strobecharging, the green lamp 228, which indicates the result of focusingfrom the object distance measuring apparatus 64, and the self-timerindicating lamp 229, which indicates the operation of the self-timer,are connected to the CPU 210.

In an EEPROM 230, data inherent to the camera at the time of assembling,such as regarding AE adjustment thereof, or data set by a photographer,such as the exposure mode or the number of frames photographed, arestored.

As shown in FIG. 31, the zoom code information input circuit (electricalcircuit) 219 is provided with four resistors (R0, R1, R2, R3) connectedin series. The resistor R0 is grounded while a reference voltage V_(DD)is applied to the resistor R3. Between the resistor R0 and ground theelectrode pattern ZC0 is connected, and between resistors R0 and R1 theelectrode pattern ZC1 is connected, between resistors R1 and R2 theelectrode pattern ZC2 is connected, and between resistors R2 and R3 theelectrode pattern ZC3 is connected. In addition, the output V_(o) of thezoom code information input circuit 219 is connected between theresistors R2 and R3. The output V_(o) is connected to an A/D conversioninput port of the CPU 210.

As shown in FIG. 30 (A), the code plate 13a is provided with fourindependent electrode patterns (zoom codes) ZC0, ZC1, ZC2 and ZC3 formedon an insulating substrate 13b. The electrode patterns, namelyconducting plates, ZC0, ZC1, ZC2 and ZC3 are connected respectivelybetween the resistors R0, R1, R2 and R3. The contacting terminal 9 isprovided with a pair of brushes 9a conducting with each other via aconductive part 9b. The brushes 9a are formed to move in slidablecontact along the code plate 13a, so that any two patterns among theelectrode patterns ZC0, ZC1, ZC2 and ZC3 may conduct with each other.Therefore, if any two patterns among the electrode patterns ZC0, ZC1,ZC2 and ZC3 conduct with each other, according to the combination ofconduction, the output voltage of the zoom code information inputcircuit 219 will vary, as shown in FIG. 30 (C) and FIG. 30 (E). The CPU210 makes an A/D conversion and whereby the output voltage is convertedinto a digital value. The CPU 210 further converts the converted digitalvalue into a corresponding zoom code. The CPU 210 then detects theposition of the zoom lens according to the zoom code.

In the present embodiment, as shown in FIG. 30 (D), the voltagescorresponding to the contacting positions of the brushes 9a areconverted into seven zoom codes, namely 0, 1, 2, 3, 4, 5 and 6. Each ofthe seven codes represents a position, i.e., the zoom code 1 representsthe housed position, the zoom code 2 the "wide" position, the zoom code6 the "tele" position, the zoom codes 3 through 5 represent theintermediate positions between the "wide" position and the "tele"position, and the zoom code 0 represents the position between the housedposition and the "wide" position. At the intermediate positions, thezoom codes 3, 4 and 5 are repeated four times in that order, and thezoom range is divided and coded into fourteen zoom step codes. In thepresent embodiment, the zoom step 0 is assigned to the "wide" endposition, and the zoom step 13 at the "tele" end position, and the zoomsteps 1 through 12 are assigned to positions between the "wide" end andthe "tele" end positions.

FIG. 31 shows the zoom code information input circuit 219 with exemplaryvalues for the resistors R0, R1, R2 and R3. FIG. 32 is a table showingan example of the relationship among the short-circuiting of resistorsR0, R1, R2, R3; the zoom code; the output V_(o) of the zoom codeinformation input circuit 219; and the threshold voltages.

The zoom pulse input circuit 220 is provided with an encoder consistingof the photointerrupter 1 and the rotating plate 2. The input of thephotointerrupter 1, varied according to the passage of the slit of therotating plate 2 which rotates in accompaniment to the rotation of thedriving shaft of the whole unit driving motor 25, is output as a zoompulse.

The AE pulse input circuit 221 is provided with an encoder consisting ofthe photointerrupter 57 and the rotating plate 59. The input of thephotointerrupter 57, varied according to the passage of the slit of therotating plate 59 which rotates in accompaniment to the rotation of thedriving shaft of the AE motor 29, is output as an AE pulse. The rotatingplate 59 having the slit is arranged so as to rotate by less than onefull turn.

The AF pulse input circuit 222 is provided with an encoder consisting ofthe photointerrupter 56 and the rotating plate 58. The input of thephotointerrupter 56, varied according to passage of the slit of therotating plate 58 which rotates in accompaniment to the rotation of thedriving shaft of the rear lens group driving motor 30, is output as anAF pulse.

The AF home position detecting circuit 232 detects whether the rear lensgroup L2 is positioned at the reference position, namely the positionclosest to the front lens group L1 (i.e., the AF home position). In thepresent embodiment, the position of the rear lens group L2 is controlledby the AF pulse number, with respect to the AF home position. The AFhome position detecting circuit 232 is provided with a photointerrupter301, and the position at which a chopper 302 (i.e., a chopper plate302a), which moves integrally with the rear lens group L2, blocks thelight path of the photointerrupter 301, is set as the AF home position,and according to the variation of output of the photointerrupter 301,the rear lens group L2 is detected to be at the AF home position.

FIG. 33 illustrates an electrical circuit of the strobe device 231.

A strobe circuit 500 is provided with a ground terminal GND, a voltageinput terminal VBAT, and three strobe controlling terminals STRG, CHENand RLS.

The battery voltage of the camera is supplied to the terminals VBAT andGND. The controlling terminals STRG, CHEN and RLS are respectivelyconnected to the CPU 210.

The terminal STRG is a strobe flashing signal (strobe trigger) inputterminal, and in an normal state the terminal STRG is set to the level L(i.e., low), and on occasion of strobe flashing, a signal at the level H(i.e., high) is input. To the terminal CHEN the charging signal isinput. At the state L, charging is not performed, while at the state H,charging is performed. The terminal RLS is a charging voltage outputterminal and outputs the voltage corresponding to the charging voltageto the A/D converter of the CPU 210.

The battery charging and the monitoring of the charging voltage will nowbe described.

As above described, the charging is performed by making the level of theterminal CHEN H (i.e., the charging signal "ON"). When the terminal CHENis at the level H, the level of the base of a transistor 501 becomes Hand transistor 501 turns ON. When the transistor 501 is ON, a voltagetransforming circuit (i.e., a DC-DC converter), consisting of atransistor 502, a primary winding 511 and a secondary winding 512 of atransformer 510, and a diode 521, is activated, and charging of acapacitor 530 is performed.

In addition, since the signal at the level H is supplied to the terminalCHEN when charging is performed, transistors 573 and 576 also turn ON,and a Zener diode 570 becomes connected to each terminal of thecapacitor 530 via a transistor 576 and resistors 577 and 578.

In the present embodiment, the capacitor 530 is charged up to 300 volts,and the break down voltage of the Zener diode 570 is 230 volts. As thecapacitor 530 is charged and the voltage applied to the Zener diode 570becomes higher than the Zener voltage (i.e., the break down voltage) ofthe Zener diode 570, the Zener current flows.

As the Zener current flows, voltage corresponding to the charged voltageof the capacitor 530, but divided by the resistors 577 and 578 isapplied to the terminal RLS.

As described above, when the terminal CHEN is at the level H in order tocharge the capacitor 530, the Zener diode 570 and the resistors 577 and578 are connected, in series, to each terminal of the capacitor 530.Until the charged voltage of the capacitor 530 exceeds the break downvoltage of the Zener diode 570, current does not flow. As charging ofthe capacitor 530 is continued, and when the voltage applied to thezener diode 570 reaches the break down voltage (i.e., 230 V), adifference between the charged voltage of the capacitor 530 and thebreak down voltage of the Zener diode 570 is divided by the resistors577 and 578, and the divided voltage value, which corresponds to thevoltage across the resistor 778 is applied to the terminal RLS.

As shown in FIG. 29, the voltage applied to the terminal RLS is input tothe CPU 210. Specifically, the voltage applied to the terminal RLS isapplied to an A/D converter built in the CPU 210, and then, based on theconverted value, the CPU 210 is capable of detecting the charged voltageof the capacitor 530. For reference, a diode 507 is a protecting diodefor preventing the transistor 501 from exceeding the withstandingvoltage, and a circuit consisting of a capacitor 503, a resistor 504 anda coil 513 stabilizes the transforming operation of the voltage.

If the CPU 210 detects that the charged voltage of the capacitor 530 hasreached the maximum charged voltage (i.e., 300 volts), the CPU 210disables the charging operation by outputting the level L signal to theterminal CHEN. When the terminal CHEN is at the level L, the transistors501 and 502 are OFF, and accordingly, charging of the capacitor 530 isnot performed. In addition, when the terminal CHEN is at the level L(i.e., the charging signal "OFF"), the transistors 573 and 577 are alsoOFF, and in that condition, the resistors 577 and 578 are disconnectedfrom the capacitor 530. Accordingly, the charging voltage of thecapacitor 530 can not be detected from the terminal RLS. As describedabove, since charging and detection of the charged voltage of thecapacitor 530 are simultaneously enabled/disabled by the signal appliedto the terminal CHEN.

The strobe flashing operation will now be described.

When the charging voltage of the capacitor 530 is more than or equal tothe level necessary for flashing, by inputting the strobe trigger to theterminal STRG, strobe flashing is performed.

When the strobe trigger is input to the terminal STRG, in other words,when the signal at the level H is input to the terminal STRG, an SCR(i.e., a thyristor) becomes in a conductive state. At that time, inaccordance with the sudden discharge of a capacitor 544 connected to theprimary winding 511 of a transformer 550, a high voltage is induced inthe secondary winding 512 of the transformer 550. The high voltage inthe secondary winding 512 is applied to a trigger electrode 551 of axenon tube 560, and flashing of the xenon tube 560 is performed.

FIGS. 37 through 40 illustrate the structure to detect the AF homeposition as the initial position of the rear lens group L2. The AF homeposition is the initial position of the rear lens group L2, close to thefront lens group L1. By making this position the reference position forfocusing, the rear lens group L2 moves along the optical axis away fromthe front lens group L1. When the power is "ON", when the shutterrelease has completed, when the lens is housed, and at the zoom steppositions other than the zoom steps 0 through 4, the rear lens group L2is controlled to maintain the AF home position with respect to the frontlens group L1, and at the zoom steps 0 through 4, the rear lens group L2is moved to the rearward position from the AF home position by an amountcorresponding to the specified pulse value AP1.

The rear lens supporting barrel 50 is supported, via the pair of slideshafts 51 and 52, so as to be capable of moving towards the shuttermounting stage 40 along the optical axis. One end of the slide shafts 51and 52 are fixed on shaft supporting bosses 50b and 50c projecting fromthe outer periphery of the lens supporting barrel 50. The slide shaft 51is inserted to be slidably supported by a slide bearing 51a fixed to theshutter mounting stage 40.

One end of the screw shaft 43 is fixed to a shaft supporting boss 50aprojecting from the outer peripheral face of the lens supporting barrel50, close to the shaft supporting boss 50b. The screw shaft 43 isengaged with the driving gear 42a, which is supported by the shuttermounting stage 40 and the shutter 27, such as to be rotatable, but notmovable in the axial direction. When the driving gear 42a is driven bythe rear lens group driving motor 30, the screw shaft 43 moves forwardlyand rearwardly with respect to the driving gear 42a, and the lenssupporting barrel 50, namely the rear lens group L2 supported by thelens supporting barrel 50, is moved relative to the front lens group L1.In order to prevent backlash between the screw shaft 43 and the drivinggear 42a, the rear lens group urging coil spring 3 is tilted to theslide shaft 51 and is engaged with the slide bearing 51a and the shaftsupporting boss 50b. The rear lens group urging coil spring 3 forces thelens supporting barrel 50 in the direction away from the shuttermounting stage 40, in other words, towards the rear of the shuttermounting stage 40. Thus backlash is prevented.

At the front of the shutter mounting stage 40, namely the presser 55,the photointerrupter 301 and the chopper 302 which comprise the AF homeposition detecting circuit 232, are mounted. The photointerrupter 301 ismounted to the flexible printed circuit board 6, and is fixed on theshutter mounting stage 40. The chopper 302 is slidably supported by achopper guide shaft 303 and has its front end supported by the presser55, while being urged towards the shutter mounting stage 40, in otherwords, rearwards in the optical axis direction, by a chopper urgingspring 304 mounted between the chopper 302 and the presser 55. Thechopper 302 is provided with the chopper plate 302a, which is insertedin the slit of the photointerrupter 301, and when the chopper 302 is atthe rearward position owing to the force of the chopper urging spring304, the optical path of the photointerrupter 301 is open, and when thechopper 302 moves to the specified position against the force of thechopper urging spring 304, the optical path of the photointerrupter 301is blocked.

At the ends of the screw shaft 43 and one of the slide shaft 51, astopper plate 306 is fixed via a lock washer 305. Provided integrally onthe stopper plate 306, a chopper presser 306a, which is contacted withthe chopper 302 and moves the chopper 302 forwardly against the force ofthe chopper presser urging 304 when the lens supporting barrel 50 movesforwardly, is formed. The chopper presser 306a is also contacted with aprojection 302b of the chopper 302 when the lens supporting barrel 50(i.e., the rear lens group L2) reaches a predetermined position closerto the shutter mounting stage 40, and owing to the further forwardmovement of the lens supporting barrel 50, the chopper presser 306amoves the chopper 302 against the force of the chopper urging spring304. When the lens supporting barrel 50 moves to the AF home positionclose to the shutter mounting stage 40, the chopper plate 302a of thechopper 302 blocks the optical path of the photointerrupter 301. Bychecking the output of the photointerrupter 301, the CPU 210 detectswhether the rear lens group L2, namely the lens supporting barrel 50, isat the AF home position or not.

In regard to the function of the present zoom lens camera, the followingdiscussion will be made with reference to flow charts shown in FIGS. 41through 73. The processes are executed by the CPU 210 based on theprogram memorized in the internal ROM of the CPU 210.

The Main Process!

FIG. 41 is a flow chart showing the main process of the camera. When thebattery is loaded into the camera, the CPU 210 commences the mainprocess, and then enters a standby state and waits for an operation tobe performed by the photographer.

In the main process, the reset process (FIG. 42), indicated at stepS0001, is executed. In the reset process, hardware initialization, suchas each port of the CPU 210, RAM initialization, test function process,reading of adjustment data, shutter initialization, AF lensinitialization, and lens housing processing, are executed.

After completion of the reset process, at step S0003 through step S0053,checks are executed to check whether the error flag is set, whether therewind switch 216 is ON, whether the state of the rear cover switch 213changes, whether the power is ON, whether the state of the power switch212 changes from OFF to ON, whether the "tele" switch 62T is ON, whetherthe "wide" switch 62W is ON, whether the driving switch 215 is changedfrom OFF to ON, whether the mode switch 214 is changed from OFF to ON,whether the photometering switch SWS is changed from OFF to ON, andwhether the charging demand flag is set, and the processes according tothe result of the checks are executed.

At step S0003, if the error flag is set (i.e., error flag is set to 1),it indicates that an error has occurred at least one of the aboveprocesses in the reset process. To clear the error flag, errorinitialization processes from steps S0005 through S0013 are repeateduntil the error flag has cleared. At step S0005 the CPU 210 waits for avariation of any of the switches, and after a variation, at steps S0006through S0009, the error flag is reset, a shutter initialization process(FIG. 51) and an AF lens initialization process (FIG. 43) are executed.Then at step S0011 it is checked as to whether the error flag has beenset during the above processes (S0006-S0009), and if the error flag isset, control returns to step S0003 and the processes from step S0005 arerepeated. If the error flag is not set at step S0011, it means that theerror state has been resolved, and control returns to step S0003 after alens housing process (FIG. 44) has been executed at step S0013.

When the error flag is cleared, and when the power is OFF, at stepS0015, step S0019, step S0023, step S0025 and step S0029, theabove-mentioned checks are repeated, namely it is checked whether therewind switch 216 is ON, whether the state of the rear cover switch 213has changed, whether the power is ON, and whether the power switch 212is changed from OFF to ON. When the rewind switch 216 is turned ON, orwhen the state of the rear cover switch 213 is changed, or when thepower switch 212 is changed from OFF to ON, the following processes areexecuted.

At step S0015, if the rewind switch 216 is ON, the rewind motor isdriven and the film rewind is executed at step S0017.

At step S0019, if the state of the rear cover switch 213 changes, namelythe rear cover is closed or opened, the rear cover processes, such asresetting of the film counter or the film loading process, are executedat step S0021.

At steps S0023 and S0025, if the power switch 212 is changed from OFF toON, the power is made ON, and the lens extension process is executed atstep S0027. Each time the power switch is turned ON, the CPU 210 turnsthe power ON if the power is OFF, and turns the power OFF if the poweris ON.

When the power is ON, control proceeds from step S0023 to step S0029,and the processes from steps S0029 to S0053 are executed. In theprocesses from steps S0029 to S0053, checks are made as to whether thepower switch 212 is varied from OFF to ON, whether the "tele" switch 62Tis ON, whether the "wide" switch 62W is ON, whether the driving switch215 is varied from OFF to ON, whether the mode switch 214 is varied fromOFF to ON, whether the photometering switch SWS is varied from OFF toON, and whether the charging demand flag is set.

At step S0029, if the power switch 212 is varied from ON to OFF, thepower is made OFF, and the lens housing process (FIG. 44) is executed atstep S0031. In the lens housing process the lens barrel is withdrawn tothe housing position.

At step S0033, if the "tele" switch 62T is turned ON, a zoom "tele"movement process (FIG. 47) is executed at step S0035. In the zoom "tele"movement process the whole unit driving motor 25 is driven in the lensextension direction.

At step S0037, if the "wide" switch 62W is turned ON, a zoom "wide"movement process (FIG. 48) is executed at step S0039. In the zoom "wide"movement process the whole unit driving motor 25 is driven in the lensretraction direction.

At step S0041, if the driving switch 215 is varied from OFF to ON, adrive setting process is executed at step S0043. Though not shown indetail, the drive setting process is a process to select the drivingmode from amongst the frame photographing mode, the continuousphotographing mode, the multiple exposure mode, the self-timer mode, orthe like.

At step S0045, if the mode switch 214 is varied from OFF to ON, a modesetting process is executed at step S0047. Though not shown in detail,the mode setting process is a process to select the exposure mode fromamongst the strobe autoflashing mode, the forced strobe flashing mode,the strobe flashing prevention mode, the red-eye reduction mode, thelong exposure mode, the bulb mode, or the like.

At step S0049, if the photometering switch SWS is varied from OFF to ON,a photographing process (FIG. 49) is executed at step S0051.

At step S0053, if the charging demand flag is set, a main chargingprocess (FIG. 50) is executed at step S0055, and the charging process ofthe strobe device 231 is executed.

When the power is ON, the above processes from steps S0003 through S0055are repeated according to the operation of the photographer, and when nooperation is being undertaken, the standby state is maintained, i.e., astate ready for photographing.

The Reset Process!

FIG. 42 is a flow chart showing the reset process at step S0001 of themain process. In the reset process the following processes are executed,namely, hardware initialization, such as each port of the CPU 210, RAMinitialization, the calling of the test function, the reading ofadjusting data, the initialization of the shutter, the initialization ofthe AF lens, and lens housing processing.

At step S1101, the initialization of hardware, i.e., initialize thelevels of each port of the CPU 210, is executed, and at S1103 theinitialization of RAM, i.e., to clear the RAM in the CPU 210, isexecuted.

At step S1105 the test function process (FIG. 68) is executed, namelyeach function of the camera is tested by an external measuringapparatus, such as a computer, during or after assemble. In the testfunction process of the present embodiment, although commands regardingthe function to be tested are output from the external measuringapparatus, the actual process is executed by the CPU 210.

At step S1107, adjusting data is read from the EEPROM 230. The adjustingdata includes exposure adjusting value data, focus adjusting value data,and diaphragm adjusted data. The exposure adjusting value data adjustsfor an error between a design diaphragm value and the actual diaphragmvalue, or adjusts for differences due to different lenses havingdifferent transmittances, and is stored before shipment of the camera.The diaphragm adjusted data detects whether or not the differencebetween the designed degree of opening of the shutter blade and theactual degree of opening thereof, has been adjusted for with respect tothe number of AE pulses detected by the AE encoder upon driving of theAE motor 29. If the adjustment has been performed, the diaphragmadjusted value is stored in the EEPROM 230, as part of the adjustingdata.

At step S1109, the shutter initialization process is executed tocompletely close the shutter blades 27a. In the present embodiment,since the opening of the shutter blades 27a is operated by the AE motor29, there is a possibility that the battery may be removed while theshutter is open, and additionally a possibility exists that the batteryis loaded while the shutter is open. Therefore, the AE motor 29 isdriven in a direction to close the shutter blades 27a (shutter closingdirection), and sets the closed condition wherein the shutter blades 27aare in contact with an initial position stopper (not shown).

At step S1111, the AF lens initialization process (FIG. 43) is executed,namely, the rear lens group L2 is moved to the initial position at whichit is extended furthest. In the present embodiment, the rear lens groupdriving motor 30 is driven to move the rear lens group L2 forwardly tothe furthest extended position, close to the front lens group L1, namelyan initial position.

At step S1113, it is checked whether the error flag has been set, and ifthe error flag has been set, control returns without executing anyfurther process, while if the error flag has not been set, controlreturns after executing a lens housing process (FIG. 44), at step S1115.

In the lens housing process, the barrier blades 48a and 48b are closedby moving the lens barrel rearwardly to the housed position within thecamera body 201, by driving the whole unit driving motor 25. Since theerror flag will be cleared during normal usage, the lens housing processwill be executed. If the error flag is set to 1, the housing(withdrawing) of the lens is stopped since it can not be guaranteed thatthe rear lens group L2 is at the initial position (i.e., the AF homeposition) in the AF initialization process, and if the lens housingprocess is executed in such a state, a possibility exists that the rearlens group L2 may collide with the aperture plate 14, so the lenshousing process is canceled.

The AF Lens Initialization Process!

FIG. 43 is flow chart showing the AF lens initialization process. In theAF lens initialization process, if the lenses are housed, the whole unitdriving motor 25 drives forward (clockwise), and the rear lens groupdriving motor 30 is connected to a barrier driving gear device (notshown), and the front lens group L1 and the rear lens group L2 are movedas a whole to the "wide" position by the whole unit driving motor 25,and then the rear lens group L2 is moved to the AF home position, namelythe position at which it will be closest to the front lens group L1, bydriving the rear lens group driving motor 30.

If the lenses are at any position other than the housed position, thewhole unit driving motor 25 is driven forward (clockwise), and if one ofthe zoom codes is detected, the rear lens group driving motor 30 isdriven and the rear lens group L2 is moved to the AF home position,namely the position closest to the front lens group L1.

However, since the rear lens group driving motor 30 is connected to thebarrier driving gear device at the housed position, and is connected tothe rear lens driving gear device at positions other than the housedposition, the whole unit driving motor 25 must be driven to move thefront lens group L1 and the rear lens group L2 to a position other thanthe housed position (i.e., to the "wide" position or further) when therear lens group L2 is to be driven.

At step S1201, the whole unit driving motor 25 is firstly driven forward(clockwise), namely in the direction for extending the lenses. If thelenses are housed, the barrier driving device is detached from thebarrier driving gear and engaged with the lens driving gear, so that therear lens group L2 is in a state capable of be driven.

At step S1203, the CPU 210 performs an A/D conversion of the voltageinput from the zoom code information input circuit 219 and converts theobtained digital value into a zoom code. At step S1205, the CPU 210checks the converted zoom code, and if the code is in the range 2through 6 at step S1205, the whole unit driving motor 25 is stoppedimmediately at step S1207. In the present embodiment, zoom code 1indicates the housed position, zoom code 2 indicates the "wide" endposition, zoom code 6 indicates the "tele" end position, zoom codes 3, 4and 5 indicate intermediate zoom positions, and zoom code 0 indicatesthe "OFF" state. In the processes of steps S1201 through S1207 the lensbarrels 16, 19 and 20 are extended until a zoom code in the range 2 to 6is detected.

At step S1209, when the whole unit driving motor 25 is stopped, an AFpulse confirmation process (FIG. 53) is executed and the rear lens groupL2 is moved to the AF home position. The AF pulse confirmation processis characterized in that the rear lens group driving motor 30 is drivento rotate in forward and reverse directions to remove so-called "biting"of the mechanical components, such as the cam follower pin into the camgroove. After the rear lens group L2 is moved to the AF home position,control is returned.

The Lens Housing Process!

FIGS. 44 and 45 show a flow chart of the lens housing process. In thelens housing process the front lens group L1 and the rear lens group L2are returned to the housed position. That is, the process is one inwhich the rear lens group L2 is returned to the AF home position by therear lens group driving motor 30, and the lenses, i.e., the front lensgroup L1 and the rear lens group L2, are driven to the housed positionby the whole unit driving motor 25, and then the lens barrier is closed.

At step S1301, when the lens housing process is called, the whole unitdriving motor 25 is driven in the forward (clockwise) direction, namelyin the "tele" zoom direction. At step S1303 the zoom code input process(FIG. 52) is executed until the present zoom code, namely the zoom codecorresponding to the lens position at the time at which the lens housingprocess is called, is detected. If the zoom code is detected at stepS1305, then at step S1307 driving of the whole unit driving motor 25 isstopped. Subsequently, at step S1309, it is judged whether or not therear lens group L2 is at the AF home position. If the rear lens group L2is not at the AF home position at step S1309, the AF return process(FIG. 54) is executed and the rear lens group L2 is moved to the AF homeposition.

If the lens housing process is performed when the rear lens group L2 isnot at the AF home position, namely the rear lens group L2 is projectingtowards the film, the rear lens group L2 may collide with the apertureplate 14 of the camera body before the lenses reach the housed position.For the purpose of avoiding such an occurrence, the rear lens group L2is returned to the AF home position before the lenses are housed, namelybefore the reverse (counterclockwise) driving of the whole unit drivingmotor 25.

When the lens housing process is called, if the lenses are positioned atthe "wide" end position, there exists a possibility that the rear lensgroup driving motor 30 may not be connected to the movement device ofthe rear lens group L2, but instead connected to the barrier openingdevice. If the rear lens group driving motor 30 is connected to thebarrier opening device, and if at the same time the rear lens group L2is extended from the AF home position, the rear lens group L2 will notmove to the AF home position even when the rear lens group driving motor30 is driven.

In the processes of steps S1301 through S1307, the lenses are drivenonce beyond the "wide" end position, to the "tele" side, as shown inFIG. 34, so that the rear lens group driving motor 30 will definitely beconnected to the driving device of the rear lens group L2 after S1307.By driving the rear lens group driving motor 30 in the AF return processat step S1311, after it has been judged at step S1309 that the rear lensgroup L2 is not positioned at the AF home position, the rear lens groupL2 can be surely be moved.

At step S1309, if the rear lens group L2 is judged to be positioned atthe AF home position, the CPU 210 skips the AF return process (stepS1311), and proceeds to the movement process for housing the lenses atstep S1312.

At step S1312, the movement of the lenses to the "wide" end is startedby driving the whole unit driving motor 25 in reverse(counterclockwise), and at step S1313 a two-second timer is started.Subsequently, at steps S1315 through S1329, before the end of thetwo-second timer, the zoom code, which varies according to the movementof the lenses, is input to detect the lenses reaching the "wide" endposition.

At step S1315, the CPU judges whether the time of the timer is up ornot. The phrase "time is up" refers to the case in which the variationof the zoom code is not detected within two seconds and where themovement of the lenses is stopped. If the time is not up, at step S1321the zoom code input process is called, and the zoom code is input.Whether the zoom code has changed is judged at step S1323, and if thezoom code has changed, the two-second timer is reset. If it is judgedthat the zoom code has not changed at step S1323, it is then judged atstep S1327 whether the lenses have reached the housed position. If thelenses have not reached the housed position, it is judged whether or notthe lenses have reached the "wide" end position at step S1329. Ifneither the housed code nor the "wide" code is detected, the CPU 210repeats the processes from step S1315.

If the time becomes up while repeating the above processes, at stepS1317 the CPU 210 stops the whole unit driving motor 25, and sets theerror flag to 1 to indicate the occurrence of an error (step S1319), andthe lens housing process is ended, and control returns to the positionat which the present process was called.

If at step S1329, the "wide" code was detected during the above process,then a four-second timer is set at step S1331, and the counter is resetto 0 (step S1335), and the processes from steps S1337 to S1361 arerepeated until the four-second timer is up. Here, a process is executedin which the rear lens group driving motor 30 is driven intermittentlywhile the whole unit driving motor 25 is driven continuously, namely thelenses are moved beyond the "wide" end position towards the housedposition.

In the camera 1 of the present embodiment, as already described, themovement of the rear lens group L2 and the opening and closing of thebarrier are executed by the rear lens group driving motor 30. When thelenses are positioned on the "tele" side of the "wide" end position, therear lens group driving motor 30 is connected to the driving device ofthe rear lens group L2 and is not connected to the barrier openingdevice. However, when the lenses are positioned toward the housedposition from the "wide" end position, when the lenses are being housed,the barrier/lens switching gear device must be switched so that the rearlens group driving motor 30 is connected to the barrier opening device.

Although the switching of the gears is designed to be executed throughthe cam device according to the movement of the lenses, in order toensure that the barrier/lens switching gear device will surely beengaged with the teeth of the barrier driving gear without fail at thistime, the rear lens group driving motor 30 is driven while the lensesare being moved from the "wide" end position to the housed position,namely after step S1311 where the reverse (counterclockwise) driving ofthe whole unit driving motor 25 is commenced, the rear lens groupdriving motor 30 is designed to be driven intermittently.

At step S1337, it is judged whether or not the time of the four-secondtimer is up. The time of the four-second timer will not be up as long asan error has not occurred, and an N (NO) judgment is normally made atstep S1337. At step S1345, after waiting 1 ms, the counter isincremented at step S1347, and it is judged whether or not the value ofthe counter has reached 100 at step S1349. If the value of the counteris less than 100, an N judgment is made at step S1349, and then at stepS1351, it is judged whether or not the value of the counter has reached80 at step S1351.

If the value of the counter is less than 80 at step S1351, the zoom codeinput process is called and the zoom code is input at step S1359. If thehoused code is not detected at step S1361, control returns to step S1337and the processes are repeated. At step S1351, when the value of thecounter reaches 80, the reverse (counterclockwise) driving of the rearlens group driving motor 30 is executed at step S1353. If the value ofthe counter reaches 100, the counter is reset to 0, and the rear lensgroup driving motor 30 is stopped, at steps S1355 and S1357.

Since the waiting time of 1 ms is set at step S1345, the above processesare repeated at a 100 ms cycle. Therefore, when the value of the counteris between 0 and less than 80, namely, until 80 ms passes after thedetection of the "wide" end code, only the whole unit driving motor 25is driven. When the value of the counter is 80 or more and less than100, namely, 80 ms or more and less than 100 ms have passed since thedetection of the "wide" end code, both the whole unit driving motor 25and the rear lens group driving motor 30 are driven. When the value ofthe counter reaches 100, namely, 100 ms have passed, the driving of therear lens group driving motor 30 is stopped and only the whole unitdriving motor 25 is driven continuously. Since the above processes arerepeated, during the driving of the whole unit driving motor 25, therear lens group driving motor 30 is driven for 20 ms in each 100 msperiod.

If the housed code is not detected before the time of the four-secondtimer is up, the time is judged to be up at step S1337. The housed codewill not be detected within four seconds if the movement of the lens isobstructed for some reason, and in such a case, at steps S1339 andS1341, the rear lens group driving motor 30 and the whole unit drivingmotor 25 are stopped, and the process is ended upon setting the errorflag to 1 to indicate the occurrence of an error.

During the above process, when the housed code is detected, the CPU 210stops the rear lens group driving motor 30 at step S1363, and furtherstops the whole unit driving motor 25 at step S1365, and after closingthe barrier by calling the barrier closing process, the lens housingprocess is completed. The barrier closing process is the process toclose the lens barrier by the rear lens group driving motor 30.

The Lens Extension Process!

FIG. 46 shows a flow chart of the lens extension process. In the lensextension process, when the state of the camera changes from being inthe standby state to the power "ON" state (i.e., the operation state),the lens barrier is opened and the lenses (i.e., the front lens group L1and the rear lens group L2) are extended from the housed position to the"wide" end position.

When the lens extension process is called, at step S1401 the barrieropening process is called, and the barrier is opened by driving the rearlens group driving motor 30. In the barrier opening process, if a pulseis not output from the AF pulse input circuit 222, namely, if the rearlens group driving motor 30 is not driven, the error flag is set to 1.

At step S1403, it is judged whether or not the error flag has been setto 1 in the barrier opening process. The error flag will be set to 1 ifthe barrier opening process does not end normally, and in this case, thelens extension processes after step S1405 are not executed and controlreturns. The error flag will be set to 0 if the barrier opening processis ended normally, and in this case, at step S1405 the whole unitdriving motor 25 is driven forward (clockwise) and the movement of therear lens group L2 and the front lens group L1 in the "tele" directionis started.

With the commencement of driving of the whole unit driving motor 25, theCPU 210 starts the four-second timer at step S1407, and monitors whetheror not the "wide" end code (i.e., whether or not the lenses reach the"wide" end position) is detected before the time of the timer is up.

At step S1409, the CPU 210 judges whether the time of the timer is up ornot. Normally, since the lenses reach the "wide" end position withinfour seconds from starting of the lens extension, the judgment at stepS1409 is "N". At step S1415 the zoom code input process is called, andat step S1417 it is judged whether or not the input code, namely, thezoom code corresponding to the lens position, is the "tele" end code,and if the input code is not the "tele" end code, at step S1419 it isjudged whether or not the input code is the "wide" end code.

The lens moves from the housed position to the "tele" end positionwithin four seconds. Accordingly, before the time of the four-secondtimer is up, if neither the "tele" end code nor the "wide" end code isdetected, it will mean, for example, that the movement of the lens isobstructed. Therefore, if at step S1409 the time is judged to be upduring the lens movement, at step S1411 the driving of the whole unitdriving motor 25 is stopped, and at step S1413 the error flag is set toindicate that an error has occurred, and the lens extension process isended.

In the normal lens extension process, when the lenses are extended, the"wide" end code is firstly detected. At step S1419, if the "wide" endcode is detected, then at step S1423 the zoom step, which is anindicator of the lens position, is set to 0, corresponding to the "wide"position. From step S1425, the processes for stopping the lenses areexecuted.

If the lens extension process is continued without detecting the "wide"end code, the lenses will eventually reach the end of the range ofcapable movement, and will become immovable. In the camera 1 of thepresent embodiment, during the lens extension process, the lenses willcontinue to move even without the "wide" end being detected, and whenthe "tele" end code is detected at step S1417, the movement of thelenses, namely, the processes after step S1425, will be stopped. Whenthe lenses reach the "tele" end position, the zoom step is set to 13,corresponding to the "tele" end position, at step S1421. Therefore,during the lens extension process, the zoom step will be set to thecorrect value corresponding to the lens position even when the lenseshave moved to the "tele" end.

As described above, when the lenses have been extended and the zoom stephas been set to correspond to the lens position, from steps S1425 toS1435 the processes to stop the lenses are executed. In the camera ofthe present embodiment, in order to obtain the position of the lens, thezoom step is set upon detecting the zoom code, but when the lenses arestopped, for the purpose of detecting the zoom code, the brush 9a isdesigned so as to stop at a position that is shifted towards the "wide"end position by a predetermined amount, namely, "the standby position".When the lenses are moved for the purpose of zooming or focusing, thelenses are moved once towards the "tele" side, regardless of whether thedirection of movement is towards the "wide" end or the "tele" end, inorder for the brush 9a to contact the zoom code. The zoom code is theninput to the CPU 210, which then controls the amount of movement of thezoom lens based on the position at which the zoom code is input, i.e.,by making the position at which the zoom code is input a referenceposition.

At step S1425, a first zoom pulse ZP1 having a predetermined value, isset in the zoom pulse counter and the zoom driving process is called, asshown in FIG. 57. In the zoom driving process, the whole unit drivingmotor 25 is driven forward (clockwise), namely, in the direction inwhich the lenses are moved toward the "tele" side, until the number ofpulses output to the CPU 210 by the zoom pulse input circuit 220, insynchronization with the rotation of the whole unit driving motor 25,becomes equal to the value of the counting set in the zoom pulsecounter. Thus, the lenses will be stopped upon being moved furthertowards the "tele" position by a predetermined amount from the positionat which the zoom code detecting terminal detects the zoom code.

The value, by which the brush for zoom code detection will be moved pastthe zoom code and will be positioned without fail at a non-continuouspart on the "tele" side, when the lenses are moved by the zoom drivingprocess, is used as the first zoom pulse ZP1, to be set at the zoompulse counter at step S1425. The value of the first zoom pulse ZP1 alsosatisfies the following conditions. In the camera of the presentembodiment, the magnification of the finder optical system variesaccording to the movement of the lenses. Accordingly, the first zoompulse ZP1 is set so that the magnification of the finder will not beaffected even if the lenses are moved by an amount corresponding to thisvalue of the pulse. In the present embodiment, though the lenses movewhen the shutter button is pressed, the number of zoom pulses,corresponding to the amount of movement of the lenses at that time, isset to a value which will not exceed that of the first zoom pulse ZP1.

After the lenses are moved by an amount corresponding to the zoom pulseZP1, at step S1429 it is judged whether or not the rear lens group L2 ispositioned at the AF home position, and if the rear lens group L2 is notpositioned at the AF home position, namely, if the rear lens group L2 isextended from the AF home position at step S1429, the AF return processis called at step S1431 and the rear lens group L2 is moved to the AFhome position. With the rear lens group L2 being positioned at the AFhome position, the AF two-stage extension process at step S1433, and thezoom return process at step S1435, are executed and control returns.

The AF two-stage extension process is the process in which the rear lensgroup L2 is extended by a certain amount from the AF home position. Inthe camera, when photography is performed (when the shutter button isdepressed fully), after the front lens group L1 and the rear lens groupL2 have been moved simultaneously for zooming, in addition to themovement of the front lens group L1 and the rear lens group L2 by thewhole unit driving motor 25, the movement of only the rear lens group L2by the rear lens group driving motor 30 is also performed for thepurpose of focusing and adjustment of the focal length.

At photographing, since the amount of movement of the rear lens group L2is relatively large when the lenses are at the "wide" end side, therelease time lag, which is the time difference between the point atwhich the shutter button is pressed and the point at which exposure isactually performed, becomes rather long. In order to shorten the releasetime lag, in the camera of the present embodiment, when the lenses arepositioned at the "wide" side, where the movement of the rear lens groupL2 is relatively large, the rear lens group L2 is extended by apredetermined amount in advance. The AF two-stage extension process isperformed for this purpose, and is the process by which the rear lensgroup L2 is extended by a predetermined amount, only when the lenses arepositioned on the "wide" side. In the present embodiment, the judgmentas to whether the lenses are on "wide" side or not, is made according towhether or not the zoom step is less than or equal to 4, which will bedescribed later (see below). In step S1434, the zoom return processmoves the lenses toward the "wide" direction by a predetermined amountcorresponding to zoom pulse ZP2 (described hereinafter).

The Zoom "tele" Movement Process!

FIG. 47 shows a flow chart of the zoom "tele" movement process. Thisprocess will firstly be described with reference to FIG. 34, which showsthe relationship between the zoom code plate 13b and the positions ofthe front lens group L1 and the rear lens group during the zoom "tele"movement process. The zoom "tele" movement process is a process to drivethe whole unit moving motor 25 in a direction in which the lens barrels16, 19 and 20 extend (i.e., in the direction in which the focal lengthis made long), namely the front lens group L1 and the rear lens group L2are advanced as a whole without changing the relative distancetherebetween.

In the zoom "tele" movement process, the zoom code corresponding to thepresent position of the lens is detected by driving the whole unitdriving motor 25 forward (clockwise). The point at which the zoom codeturns "ON" is used as a reference point when the whole unit drivingmotor 25 is to be stopped. After the whole unit moving motor 25 isdriven forward (clockwise) to advance the lenses by the predeterminedfirst zoom pulse value ZP1 with respect to this reference point, thewhole unit driving motor 25 is driven in reverse (counterclockwise).After the whole unit driving motor 25 has been driven to rotate inreverse (counterclockwise) by the second zoom pulse value ZP2 withrespect to the point at which the zoom code turns "ON/OFF" again, thewhole unit driving motor 25 is driven forward (clockwise) by a backlasheliminating zoom pulse value ZP3, and the whole unit driving motor 25 isstopped. By this zoom "tele" movement process, the zoom lens is stoppedbetween zoom codes with backlash in the forwarding (advancing) directionbeing removed to some extent.

Furthermore, in the present embodiment, when the whole unit drivingmotor 25 stops, if the zoom step is not more than 4, the rear lens groupL2 is retracted by an amount corresponding to the predetermined AF pulsevalue AP1. In the present embodiment, the present lens position iscontrolled by dividing the focal length range, from the "wide" end tothe "tele" end, into fourteen parts, and assigning the zoom step 0 tothe "wide" end, the zoom step 13 to the "tele" end, and zoom steps 1through 12 to the focal lengths in between.

In the zoom "tele" movement process, at step S1501 it is checked whetheror not the lenses are at the "tele" end position, and if the lenses areat the "tele" end position, control returns since there is no need fortele-zooming.

If the lenses are not at the "tele" end position at step S1501, at stepS1503 the whole unit driving motor 25 is driven forward (clockwise),namely, in the tele-zoom direction, and the zoom code input process isexecuted at step S1505, and waiting is performed until the present zoomcode corresponding to the zoom step is detected at step S1507. When thepresent zoom code corresponding to the zoom step is detected, at stepS1509 a two-second timer is started to detect a state in which the wholeunit driving motor 25 is incapable of driving for a predetermined periodof time (i.e., two seconds).

When the two-second timer is started, at step S1511 it is checkedwhether or not the time is up. In the case of normal operations the timewill not be up, and therefore at step S1513 the zoom code input processis executed. Then at step S1515 it is checked whether or not the zoomcode has changed, and if the zoom code has not changed, a "tele" endcode detecting check is directly executed at step S1519, while if thezoom code has changed, the "tele" end code detecting check is executedat step S1519 only after restarting the two-second timer at step S1517.

If the zoom code does not change even after the whole unit driving motor25 has driven for the predetermined period of time, it is assumed thatan abnormal condition, such as the lens barrel has contacted someobject, has occurred. Therefore at steps S1511, S1537 and S1539, afterstarting the two-second timer, if the two seconds have elapsed and thetime of the two-second timer is up without any variation of the zoomcode, the whole unit driving motor 25 is stopped, and the error flag isset, and control is returned.

If the "tele" end code is not detected at step S1519, it is judgedwhether or not the next zoom code is detected at step S1521, and if thenext code is not detected, the processes of steps S1511 through S1519are repeated. Upon detection of the next zoom code, the zoom step isincremented by 1 at step S5123, and if the "tele" switch 62T is ON atstep S1525, control is returned to step S1511 and the above processesare repeated, while if the "tele" switch is OFF, a jump to step S1525 isperformed. That is, once this process is entered, tele-zooming isperformed by one zoom step even when the zoom switch 62T is turned OFFbefore tele-zooming is performed by one zoom step.

A jump to step S1529 is performed when the lenses reach the "tele" endor when the "tele" switch 62T is turned OFF (steps S1525, S1529 orS1519, S1527, S1529). If the jump is performed upon reaching the "tele"end, the zoom step is set to 13 at step S1527.

At step S1529, the predetermined first zoom pulse value ZP1 is set inthe zoom pulse counter. Then after the zoom driving process at stepS1531, the AF two-stage delivery process (step S1533) and the zoomreturn process (step S1535) are executed, and control is returned.

In the zoom driving process, the whole unit driving motor 25 is drivenforward (clockwise) (i.e., in the direction in which the lenses areextended) by an amount corresponding to the value of the zoom pulsecounter, namely, that of the first zoom pulse value ZP1.

In the AF two-stage extension process, when the whole unit driving motor25 is stopped, if the zoom step is not more than 4, the rear lens groupL2 is retracted by an amount corresponding to the predetermined AF pulsevalue (i.e., AP1). Then the whole unit driving motor 25 is driven inreverse (counterclockwise), by an amount corresponding to the secondzoom pulse value ZP2, with respect to the point at which the zoom codeturns ON/OFF, and after that, the whole unit driving motor 25 is drivenforward (clockwise) by an amount corresponding to the backlasheliminating third zoom pulse value ZP3, and then the whole unit drivingmotor 25 is stopped. By this zoom "tele" movement process, the zoom lensis stopped between zoom codes with the backlash in the advancingdirection being somewhat eliminated.

In the zoom return process, the whole unit driving motor 25 is driven inreverse (counterclockwise), and is further driven in reverse(counterclockwise) by an amount corresponding to the second zoom pulsevalue ZP2 with respect to the point at which the zoom code turns ON/OFF.After that, the motor is driven forward (clockwise) by an amountcorresponding to the backlash eliminating third zoom pulse value ZP3,and then the whole unit driving motor 25, is stopped to thereby stop thefront lens group L1 and the rear lens group L2 at the standby positionbetween the zoom codes.

The Zoom "wide" Movement Process!

FIG. 48 shows a flow chart for the zoom "wide" movement process. Thisprocess shall be firstly described with reference to FIG. 34, whichshows the relationship between the zoom code plate 13b and the positionsof the front lens group L1 and the rear lens group L2 during the zoom"wide" movement process. In the zoom "wide" movement process the wholeunit driving motor 25 is driven in the direction in which the lensbarrels 16, 19 and 20 are retracted (i.e., the direction in which thefocal length is made shorter), namely, the front lens group L1 and therear lens group L2 are retracted as a whole without changing thedistance therebetween.

In the zoom "wide" movement process, the whole unit driving motor 25 isfirst driven forward (clockwise) and after being driven forward furtherby an amount corresponding to the first zoom pulse value ZP1 from thepoint at which the zoom code corresponding to the present lens positionis detected, is driven in reverse (counterclockwise). When the wholeunit driving motor 25 is stopped in the intermediate zoom region, themotor 25 is further driven in reverse (counterclockwise) by an amountcorresponding to the second zoom pulse value ZP2 from the point at whichthe zoom code turns "ON/OFF", and then the motor 25 is driven in reverse(counterclockwise) by an amount corresponding to the backlasheliminating zoom pulse value ZP3, and then the whole unit driving motor25, is stopped. By this zoom "wide" movement process, the zoom lens isstopped between zoom codes with the backlash in the forwarding(advancing) direction being somewhat eliminated.

In the present embodiment, when the whole unit driving motor stops, ifthe zoom step is not more than 4, the rear lens group L2 is retracted byan amount corresponding to the predetermined AF pulse value AP1. Themotor 25 is then driven in reverse (counterclockwise) by an amountcorresponding to the second zoom pulse value ZP2 with respect to thepoint at which the zoom code turns "ON/OFF", and then the motor 25 isdriven forward (clockwise) by an amount corresponding to the zoom pulsevalue ZP3 for backlash elimination, and then the whole unit drivingmotor 25 is stopped. By this zoom "wide" movement process, the zoom lensis stopped between zoom codes with the backlash in the advancingdirection being eliminated to some extent.

When the zoom "wide" movement process is entered, at step S1601 it ischecked whether or not the lens is at the "wide" (i.e., "wide" end)position, and if the lens is at the "wide" position, control returnssince there is no need for zooming.

If at step S1601, the lens is not at the "wide" position, the whole unitdriving motor 25 is driven forward (clockwise), i.e., tele-zoomingdirection, at step S1603 since there is a possibility that the lensesmay have been moved past the next zoom code owing to the backlash whenthe lenses were retracted. At step S1605 the zoom code input process isexecuted and waiting is performed until the present zoom codecorresponding to the zoom step is detected at step S1607. When thepresent zoom code corresponding to the zoom step is detected, the wholeunit driving motor is stopped (step S1609) and then is driven in reverse(counterclockwise) (step S1611), and the two-second timer is started atstep S1613.

When the two-second timer is started, it is checked whether or not thetime is up at step S1615. In the case of normal operations the time willnot be up, and therefore at step S1617 the zoom code input process isexecuted. It is then checked whether or not the zoom code has changed atstep S1619, and if the zoom code has changed, the two-second timer isrestarted (step S1621) and it is checked whether or not the housed codehas been detected at step S1623. If the zoom code has not changed atstep S1619 control proceeds to step S1623. If the housed code is notdetected at step S1623, it is checked whether or not the "wide" end codeis detected at step S1625, and if the "wide" end code is also notdetected, it is checked whether or not the next zoom code has beendetected at step S1627. If the next zoom code has not been detected,control returns to step S1615, and the process from steps S1615 to S1627are repeated until the next zoom code is detected.

When the next zoom code is detected at step S1627, the zoom step isdecremented by 1 at step S1629, and if the "wide" switch 62W is ON atstep S1631, control returns to step S1615 and the above processes ofsteps S1615 through S1631 are repeated. If the "wide" end code isdetected at step S1625, or if the "wide" switch is OFF, control jumps tostep S1633 and the zoom return process is called (steps S1625, S1633,S1635, S1637 or S1631, S1635, S1637). At step S1637, when the jump isperformed upon detection of the "wide" end code, the zoom step is set to0.

In the zoom return process at step S1633, the front lens group L1 andthe rear lens group L2 are returned to the standby position at whichthey were positioned before the lens driving process in thephotographing process.

In the AF two-stage delivery extension at step S1635, the rear lensgroup L2 is retracted to the AF home position, or to the positionretracted from the AF home position by an amount corresponding to thevalue AP1 in accordance with the present zoom step.

Although the above description is directed to a normal operation, incases where the lens barrel is forcibly pushed etc., it is checked atstep S1623 that the housed code has been detected and then the wholeunit driving motor 25 is stopped at step S1639, and the lens extensionprocess is executed at step S1641 before the control is returned. Inaddition, if the time becomes up at the two-second timer, for examplewhen the lens barrel is pressed and is incapable of movement, the wholeunit driving motor 25 is stopped at step S1645, and control returnsafter setting the error flag to 1.

In the present zoom "wide" process, since the "wide" switch check isexecuted after detecting the present zoom code and the next zoom code,wide zooming is performed by one zoom step once this process is entered,even when the zoom "wide" switch 62W is OFF before zooming is performedby one step.

The Photographing Process!

FIG. 49 shows a flow chart for the photographing process. Thephotographing process, of the present embodiment, is called when thephotometering switch SWS is turned ON, and is characterized in that itis first checked that the front lens group L1 is at the standbyposition, and that the front lens group L1 and the rear lens group L2are moved to positions, at which the focus will be set on the subject,at the preset focal length, after the release switch SWR is turned ON.

In the photographing process, at step S1701, the zoom standbyconfirmation process is executed, and the front lens group L1 is movedto the standby position corresponding to the present focal length.

Then at steps S1703, S1705 and S1707, the object distance measuringprocess is executed and the focal length is obtained, the photometeringprocess is executed and the luminance of the subject is obtained, andthe AE calculation process is executed to determine the shutter speed,the aperture value, and whether or not strobe flashing is necessary.Strobe flashing will be necessary when the luminance of the subject isat the strobe flashing level in the auto strobe flashing mode, or whenthe forced strobe flashing mode is set, etc. If it is judged that strobeflashing is necessary at step S1709, the photographing charging processis executed at step S1711, and during the photographing chargingprocess, if the photometering switch SWS is turned OFF or if the time ofthe charging timer becomes up (step S1713), control returns, while ifsufficient charging has been completed, after executing the flashmatic(FM) operation at step S1715, control proceeds to step S1717. If strobeflashing is not necessary at step S1709, control proceeds to step S1717,skipping steps S1711 through S1715.

At step S1717, it is checked whether the photometering switch SWS isturned ON, and if the photometering switch SWS is turned OFF, controlreturns. If the photometering switch SWS is ON at step S1717, theturning ON of the release switch SWR (step S1719) is waited for whilethe photometering switch SWS remains ON.

When the release switch SWR is ON (step S1719) and if the self-timermode is not set at step S1721, the lens drive calculation process isexecuted at step S1725. If the self-timer mode is set, the lens drivecalculation process is executed after a self-waiting process at stepS1723, in which waiting is performed for a predetermined amount of time.

In the lens drive calculation process, the amount of movement, i.e., thezoom pulse value, of the front lens group L1 with respect to the ON/OFFswitching point of the zoom code and the amount of movement, i.e., theAF pulse value, of the rear lens group L2 with respect to the switchingpoint of the AF home signal (AF home position) are calculated accordingto the result of focusing and the present focal length.

Then at steps S1725 and S1727, according to the amount of movement ofthe front lens group L1 and the rear lens group L2 obtained through thelens drive calculation process, the lens driving process is executed. Inthe lens driving process, the rear lens group L2 is driven together withthe front lens group L1, and control is performed to bring the subjectinto focus.

When the movement of the lens is completed, at step S1729 the green lamp228 is lit (i.e., current is passed through the green lamp) to notifythe photographer that the shutter will be released, and the exposureprocess is executed at step S1731. The green lamp 228 only stays lit fora small amount of time and then is turned OFF.

After the exposure process has completed, at step S1733, the lens returnprocess is executed, in which the front lens group L1 and the rear lensgroup L2 are returned to the positions they were at prior to movement atstep S1727.

Then at steps S1735, S1737 and S1739, the film winding process isexecuted, and if the film is not at its end, control is returned, whileif the end of the film has been reached, the rewinding process isexecuted and control returns.

The Main Charging Process!

FIG. 50 shows a flow chart for the main charging process. The maincharging process is the charging process that is called in the mainprocess (FIG. 41) when the charging demand flag equals 1.

At step S1801, the CPU 210 judges whether or not the value of the chargedisable timer is set 0. The charge disable timer is a timer in which thetime during which charging is disabled is set. A charge disable time ofthree seconds is set when the flash capacitor 530 of the strobe device231 is fully charged. If the time is not up at the charge disable timerat step S1801, at step S1803 the charging demand flag is set to 0, andthe process is ended. In such a manner, while the charge disable timeris counting the three seconds during which charging is to be disabled,the CPU 210 prohibits charging unconditionally without checking thecharging voltage. The charging can be interrupted (disabled) by settingthe level of the terminal CHEN of the strobe device 231 to L.

If the time at the charge disable timer is up, at step S1805 the CPU 210judges whether or not the charge interruption flag is set to 1. As willbe described later, the charge interruption flag is set to 1 when thecharging process is canceled before the completion thereof. In thepresent main charging process and in the photographing charging process,which will be described later, the charging process is deemed to havebeen completed normally when the charging voltage reaches apredetermined value, or when the charging time reaches a predeterminedtime (in the present camera, eight seconds). During charging, if thecharging is interrupted owing to the operation of another switch, etc.,the time spent on charging prior to interruption is deducted from thepredetermined time, namely from eight seconds, and the remaining time isstored in the memory, and when charging is resumed, it is judged whetheror not the charging voltage will reach the predetermined value withinthe remaining time.

Therefore, if the charge interruption flag is set to 1, the chargeinterruption flag is cleared, in other words set to 0, and a resumedcharging process is performed by setting the charging timer to theremaining time which has been stored in the memory. If the chargeinterruption flag is not 1, namely if the charging process has not beeninterrupted at step S1805, charging is performed upon setting thecharging timer to the predetermined charging, i.e., eight seconds.

In order to start charging, the CPU 210 turns ON the charging signal atstep S1813. In other words, charging is started by setting the level ofterminal CHEN of the strobe device 231 to be high (H). While the levelat the terminal CHEN on the strobe device 231 is H, an A/D conversion isperformed on the output of terminal RLS of the strobe device 231, andthe converted output is input to the CPU 210. At step S1815, the CPU 210checks the charging voltage based on the A/D converted voltage value. Ifthe charging voltage has reached the upper limit at step S1817, then atstep S1819, the CPU 210 disables charging for three seconds, by settingthree seconds as the charge disable time in the charge disable timer,and then at step S1821, the CPU 210 stops the charging by making thevoltage at the terminal CHEN of the strobe device 231 as low (L). Thenthe charging demand flag is set to 0 at step S1823 and the main chargingprocess is completed.

If at step S1817, the CPU judges that the charging voltage has notreached the upper limit, at step S1825 it is judged whether or not thetime is up at the charging timer. If the time is up at the chargingtimer, at step S1821 the charging is stopped by making the level at theterminal CHEN of the strobe device 231 as L, and at step S1823 thecharging demand flag is set to 0 to indicate the completion of thecharging process. For reference, if the main charging process iscompleted after the time of the charging timer is up, the charge disabletime of three seconds is not set.

If the time of the charging timer is not up at step S1825, then at stepS1827, the CPU judges whether the state of any of the switches haschanged. If any change of state amongst the switches is detected, thecharging process is interrupted, and the process corresponding to theoperated switch is performed with priority. Therefore, upon detecting achange in the state of the switches, the CPU 210 sets the chargingsignal to OFF at step S1829 (i.e., sets the level at the terminal CHENof the strobe device 231 to be low), and at step S1831 the remainingtime indicated by the charging timer is stored in the memory, and atstep S1835 the charge interruption flag is set 1 to indicate theinterruption of charging, and the main charging process is completed.The remaining time stored in the memory at step S1831, and the chargeinterruption flag set at step S1835, are referred to at the time ofexecution of the next main charging process or the next photographingcharging process. The Shutter Initialization Process!

FIG. 51 shows a flow chart for the shutter initialization process. Inthe shutter initialization process of the present embodiment, the AEmotor 29, which drives the shutter 27, is driven in the shutter closingdirection to fully close the shutter blades until the shutter bladescome into contact with the stoppers.

At step S1901, the AE motor 29 is firstly driven in reverse(counterclockwise) to drive the shutter blades 27a in the closingdirection. Then at step S1903 the AE pulse counting limit timer isstarted, and the AE pulse count process is called to wait for the timeto be up at the AE pulse counting limit timer, while detecting the AEpulse (steps S1905, S1907). The AE pulse counting process is performedby the CPU 210 in combination with the AE pulse inputting circuit 221.

At steps S1907 and S1909, when the shutter blades 27a are completelyshut and the AE motor 29 becomes incapable of driving, since the timewill become up at the AE pulse counting limit timer, the AE motor 29 isfreed when the time is up, and control is returned.

By the above process, the shutter 27 is set to the initial position atwhich the shutter blades 27a are completely shut.

The Zoom Code Input Process!

FIG. 52 shows a flow chart of the zoom code input process. In the zoomcode input process, the zoom code is set based on the A/D convertedvalue of the voltage input into the A/D conversion terminal of the CPU210 from the zoom code information input circuit 219.

At step S3201, the output V_(o) of the zoom code information inputcircuit 219 is input into the A/D terminal of the CPU 210. The CPU 210compares the A/D converted value of the input voltage with the thresholdvoltages Va through Vf, and sets the zoom code corresponding to theinput voltage. The setting of the zoom code is executed as follows.

At step S3203, the CPU 210 compares the A/D converted value with thethreshold voltage Va. If the A/D converted value of the input voltage isgreater than the threshold voltage Va at step S3203, the zoom code isset to 0 at step S3205, and control is returned.

If the A/D converted value of the input voltage is less than or equal toVa at step S3203, and greater than Vb at step S3207, the zoom code isset to 5 at step S3209.

If the A/D converted value of the input voltage is less than or equal toVb at step S3207, and greater than Vc at step S3211, the zoom code isset to 4 at step S3213.

If the A/D converted value of the input voltage is less than or equal toVc at step S3211, and greater than Vd at step S3215, the zoom code isset to 3 at step S3217.

If the A/D converted value of the input voltage is less than or equal toVd at step S3215, and greater than Ve at step S3219, the zoom code isset to 6 at step S3221.

If the A/D converted value of the input voltage is less than or equal toVe at step S3219, and greater than Vf at step S3223, the zoom code isset to 1 at step S3225.

If the A/D converted value of the input voltage is less than or equal toVf at step S3223, the zoom code is set to 2 at step S3227.

Here, the codes identified by Vd, Ve and Vf, for which the intervalbetween the threshold voltages is relatively large, are respectivelyassigned to the lens housed position (the zoom code=1), the "wide" endposition (the zoom code=2) and the "tele" end position (the zoomcode=6), which become reference points for the lens position. In such amanner, the correct zoom code will be set at least for the referencepoints even when the voltage input into the CPU 210 varies somewhat dueto voltage fluctuations.

The AF Pulse Confirmation Process!

FIG. 53 shows a flow chart for the AF pulse confirmation process. In theAF pulse confirmation process the rear lens group driving motor 30 isdriven alternately in the forward (clockwise) and reverse(counterclockwise) directions. For example, during driving of the rearlens group driving motor 30, if the rear lens group driving motor 30 isunable to rotate for some reason, by alternately driving the rear lensgroup driving motor 30 forward and in reverse, the cause of theobstruction of rotation of the rear lens group driving motor 30 may beremoved, thus allowing the rear lens group L2 to move. In the presentembodiment, the rear lens group driving motor 30 alternately rotatesforward and in reverse, and after confirming that the rear lens groupdriving motor 30 has rotated more than a predetermined amount, the rearlens group L2 is moved to the AF home position. If this confirmation hasnot been made within five operations of alternate forward and reversedriving, or even if such a confirmation is made, if the rear lens groupL2 does not move to the AF home position within the predetermined time,the rear lens group driving motor 30 is stopped, and the error flag isset to 1.

At step S3301, the value of the counter which defines the maximum numberof times that the rear lens group driving motor 30 is driven alternatelyin the forward (clockwise) and reverse (counterclockwise) directions isset to 5.

Then at steps S3303, S3305 and S3307, the rear lens group driving motor30 is firstly driven forward (clockwise), namely in the direction inwhich the rear lens group is retracted, the AF pulse counting process isperformed upon setting the value of the AF pulse counter to 50, andwaiting is performed until 50 AF pulses are output. When the value ofthe AF pulse counter becomes 50, at step S3309 the rear lens groupdriving motor 30 is stopped.

At step S3311 it is checked whether the OK flag is set, and if the OKflag is set, in other words if 50 AF pulses have been output, it ischecked whether or not the rear lens group L2 is at the AF homeposition. If the rear lens group L2 is at the AF home position, controlreturns, while if the rear lens group L2 is not at the AF home position,at step S3331 and step S3335 the rear lens group driving motor 30 isdriven in reverse (counterclockwise), namely in the direction in whichthe rear lens group L2 is moved towards the AF home position, and a 500ms timer is started. Since the rear lens group L2 will normally reachthe AF home position before the time of the 500 ms timer is up, the rearlens group driving motor 30 is stopped and control is returned when therear lens group L2 reaches the AF home position (steps S3335, S3337,S3339). Here, if the rear lens group L2 does not reach the AF homeposition before the time of the 500 ms timer is up, at steps S3335,S3341 and S3343, the rear lens group driving motor 30 is stopped, andcontrol is returned upon setting the error flag to 1.

Although the above is directed to a normal case, if the rear lens groupL2 does not move easily the following processes are executed.

In the AF pulse counting process at step S3307, if the AF pulse is notoutput for a predetermined amount of time even though the rear lensgroup driving motor 30 is being driven, since this will mean that acondition is occurring in which the rear lens group driving motor 30cannot move due to biting, etc., the OK flag is cleared. In this case,control proceeds to the rolling process, from steps S3311 to S3313. Whencontrol is at step S3313, after waiting for 100 ms, the rear lens groupdriving motor 30 is driven in reverse (counterclockwise) at step S3315.Then at steps S3317, S3319 and S3321, the value of the AF pulse counteris set to 50, and the AF pulse counting process is executed, and thenthe rear lens group driving motor 30 is stopped. In the AF pulsecounting process, when 50 AF pulses are detected, the OK flag is set,and if 50 AF pulses are not detected within a predetermined time, the OKflag is cleared. Thus, if the rear lens group L2 moves during suchreverse (counterclockwise) rotation of the rear lens group driving motor30, control proceeds to the process at step S3329, while if the rearlens group L2 does not move, control proceeds to the process at stepS3325.

At step S3325, the counter is decremented by one, and if the value ofthe counter is not 0, control returns to step S3303, and the processesfrom step S3303 are repeated. If the value of the counter becomes 0,namely if the rear lens group L2 is not moved even upon repeating theforward (clockwise) and reverse (counterclockwise) driving of the rearlens group driving motor 30 five times, since this will indicate thatsome form of trouble may be occurring with the lens driving system, atsteps S3341 and S3343, the rear lens group driving motor 30 is stopped,and the error flag is set to 1, and control is returned.

The AF Return Process!

FIG. 54 shows a flow chart for the AF return process. In the AF returnprocess the rear lens group L2 is returned to the AF home position.

At steps S3401 and S3403, the rear lens group driving motor 30 is drivenin reverse (counterclockwise), namely in the direction in which the rearlens group is advanced, to advance the rear lens group L2 towards the AFhome position and waiting is performed until the rear lens group L2reaches the AF home position.

At steps S3405, S3407, S3409, S3411 and S3413, when the arrival of therear lens group L2 at the AF home position is detected, via thephotointerrupter 301, the driving of the rear lens group driving motor30 is switched to low-speed reverse (counterclockwise) driving, and avalue of 10 is set in the counter. The rise of the AF pulse is thencounted and the counter is decremented by one on each count and waitingis performed until the value at the counter becomes 0.

At steps S3413 and S3415, when the value at the counter becomes 0, therear lens group driving motor 30 is stopped, and control is returned. Insuch a manner, the rear lens group L2 surely stops at the AF homeposition.

In the present embodiment, after the rear lens group L2 reaches the AFhome position, the driving of the rear lens group driving motor 30 iscontinued for another ten pulses. This is done since the driving pulsecount for the rear lens group L2 is based on the switching of the AFhome signal and so that the rear lens group L2 will definitely be at theAF home position in the standby condition.

The Barrier Closing Process!

FIG. 55 shows a flow chart for the barrier closing process. In thebarrier closing process the barrier is closed upon housing of thelenses.

Firstly, a value 3, which is the number of times the opening/closingprocess (described later) is to be repeated when a fault occurs, is setin the counter. In the present embodiment, the judgment whether thebarrier closing process is completed normally, is made according towhether the rear lens group driving motor 30 has driven forward(clockwise) by a predetermined amount, namely, whether a predeterminednumber of AF pulses have been counted upon driving the rear lens groupdriving motor 30.

During forward (clockwise) driving of the rear lens group driving motor30, if the predetermined number of AF pulses is not input from the AFpulse input circuit 222, it can be suspected that the barrier could notbe closed due to some reason, or that the barrier closing process wasexecuted with the barrier closed already.

Therefore, in the present embodiment, when the predetermined number ofAF pulses is not counted upon forward (clockwise) driving of the rearlens group driving motor 30, the rear lens group driving motor 30 isonce driven reverse (counterclockwise) by a predetermined amount, namelyby an amount sufficient for opening the closed barrier, and then therear lens group driving motor 30 is driven forward (clockwise) again.The number of times set at step S3501 is the value for restricting thenumber of times of execution of the process in which the rear lens groupdriving motor 30 is once driven reverse (counterclockwise) and thendriven forward (clockwise) again (described above).

At step S3503, the rear lens group driving motor is driven forward(clockwise), namely, driven in the direction by which the barrier willclose, and at step S3505 a value of 300 is set in the AF pulse counter,and at step S3507 the AF pulse counting process is called. In the AFpulse counting process the AF pulse counter, set at step S3505, isdecremented based on the pulse signals output to the CPU 210 from the AFpulse input circuit 222 in synchronization with the rotation of the rearlens group driving motor 30.

The AF pulse counting process is ended when the pulse is not outputwithin a predetermined time, or when the count value at the decrementedAF pulse counter becomes 0.

After completion of the AF pulse counting process, at step S3509 therear lens group driving motor 30 is stopped, and at step S3511, it isjudged whether or not the AF pulse count remaining after beingdecremented in the AF pulse 5 counting process is less than 100.

At step S3511, if the value of the AF pulse counter is less than 100,namely, if the value was decremented by 200 or more in the AF pulsecounting process, it is judged that the barrier was closed normally, andthe barrier closing process is ended. If the value of the AF pulsecounter is 100 or more at step S3511, it is considered that the rearlens group driving motor 30 cannot rotate due to some reason and theelimination of the obstruction is attempted by once rotating the rearlens group driving motor 30 in reverse (counterclockwise), and thenagain forward (clockwise). In such a manner, the obstacle can beremoved.

The control proceeds to step S3519, as long as the counter value doesnot become zero upon decrementing of the counter at step S3513. At stepS3519, the rear lens group driving motor 30 is driven in reverse(counterclockwise), and a value of 300 is set in the AF pulse counter,and the AF pulse counting process is called. After completion of the AFpulse counting process at step S3523, the rear lens group driving motor30 is stopped at step S3525, and the control returns to step S3503. Thenat steps S3503, S3505, S3507 and S3509, the forward (clockwise) drivingof the rear lens group driving motor 30, the setting of the AF pulsecounter, the execution of the AF pulse counting process, and stopping ofthe rear lens group driving motor 30 are made. It is then judged at stepS3511, whether or not the barrier has closed, based on the value of theAF pulse counter. In the present embodiment, since a value of 3 is setat the counter at step S3501, if the barrier is not closed, the aboveretrial process is repeated twice.

During the above process, if the barrier closes, at step S3511 the valueof the AF pulse counter will be less than 100, and the barrier closingprocess is completed. In addition, after repeating the process, if thevalue of the AF pulse counter does not become less than 100, after thelast of the repetitions, the barrier is judged not to be closed, and thebarrier closing process is ended upon setting the error flag to 1 toindicate an occurrence of a fault.

The Barrier Opening Process!

FIG. 56 shows a flow chart for the barrier opening process. In thebarrier opening process the barrier is opened when the lenses areextended from the housed position.

First, a value of 3, which is the number of times of repetition of theprocess, is set at the counter at step S3601. Normally, the barrieropening process is called with the barrier being closed. However, thebarrier opening process will be executed with the barrier open when, forexample, the battery of the camera is changed with the lens beingextended, i.e., the barrier is open. The barrier opening process mayalso be called when the lenses are housed without the barrier beingclosed because of some obstruction. If the rear lens group driving motor30 is driven to open the barrier when the barrier is already open, therear lens group driving motor 30 will not rotate because the barrier isopen, and the AF pulse input circuit 222 will therefore not generate anypulses.

Therefore, in the present process, the rear lens group driving motor 30is firstly driven in order to open the barrier, and if the opening ofthe barrier is not confirmed, in other words, if the AF pulse inputcircuit 222 does not output pulses to the CPU 210, the rear lens groupdriving motor 30 is once driven in the direction to close the barrier,and is again driven in the direction to open the barrier. The number oftimes set at the counter at step S3601 is the value for restricting thenumber of times of execution of the above-described process in which thebarrier is opened again after closing it once, which is executed when itcannot be confirmed that the barrier was opened upon driving the rearlens group driving motor 30 for the first time.

At step S3603, the rear lens group driving motor is firstly driven inreverse (counterclockwise), namely, in the direction in which thebarrier opens, and at step S3605 a value of 300 is set in the AF pulsecounter, and at step S3607 the AF pulse counting process is called. Inthe AF pulse counting process the AF pulse counter is decremented basedon the pulse signals output to the CPU 210 from the AF pulse inputcircuit 222 in synchronization with the rotation of the rear lens groupdriving motor 30.

The AF pulse counting process is ended when the pulses are not output tothe CPU 210 from the AF pulse input circuit 222 within a predeterminedtime, or when the count value of the decremented AF pulse counterbecomes 0.

After completion of the AF pulse counting process, at step S3609 therear lens group driving motor 30 is stopped, and at step S3611, it isjudged whether or not the AF pulse count remaining after beingdecremented in the AF pulse counting process is less than 100.

At step S3611, if the value of the AF pulse counter is less than 100,namely, if the value was decremented by 200 or more in the AF pulsecounting process, it is judged that the barrier was opened normally, andthe barrier opening process is ended. If the value of the AF pulsecounter is 100 or more at step S3611, it is considered that the rearlens group driving motor 30 cannot rotate due to some reason and theelimination of the obstruction is attempted by once rotating the rearlens group driving motor 30 forward (clockwise), namely, in thedirection in which the barrier closes, and then again in reverse(counterclockwise). In such a manner, the obstacle shall be removed.

At step S3613, the counter is decremented, and as long as the counterdoes not become 0 at step S3615, control proceeds to step S3619. At stepS3619, the rear lens group driving motor 30 is driven forward(clockwise), a value of 300 is set in the AF pulse counter, and the AFpulse counting process is called. After completion of the AF pulsecounting process at step S3623, the rear lens group driving motor 30 isstopped at step S3625, and control is returned to step S3603. Then thereverse (counterclockwise) driving of the rear lens group driving motor30, the setting of the AF pulse counter, the execution of the AF pulsecounting process, and the stopping of the rear lens group driving motor30 are made, and it is judged whether or not the barrier is closed,according to the value of the AF pulse counter.

In the present embodiment, since the value of 3 is set in the counter atstep S3601, if the barrier is not opened at step S3611, the processesfrom steps S3613 to S3609 via S3625 are repeated twice. If the barrieropens in this process, the AF pulse counter will be less than 100 atstep S3611, and the barrier opening process is ended. If the value ofthe AF pulse counter does not become less than 100 after the last of therepetitions, it is judged that the barrier did not open and the barrieropening process is ended upon setting the error flag to 1 to indicatethe occurrence of a fault.

The Zoom Driving Process!

FIG. 57 shows a flow chart for the zoom driving process. The zoomdriving process is a process to drive and control the whole unit drivingmotor 25 forward (clockwise) (i.e., in the direction in which the lensesare extended) by the amount corresponding to the value of the zoom pulsecounter, in order to cause the front lens group L1 and the rear lensgroup L2 to become focused at the subject distance, as shown in FIG. 34.

In the zoom driving process, at step S3701 the value of the zoom pulsecounter is firstly stored in memory as the number of zoom pulses. Thenat steps S3703, S3705, S3707 and S3709, the zoom sequence is then set to0 and the whole unit driving motor 25 is driven forward (clockwise),namely, in the advancing direction, the zoom drive check process isexecuted, and waiting is performed until the zoom sequence becomes 5,and control is returned when the zoom sequence becomes 5.

The zoom sequence is an identifier for identifying the operationsequence condition of the whole unit driving motor controlling circuit60. A zoom sequence of 0 indicates that the switching of the zoom code,which serves as the reference point for the counting of the zoom pulses,has been detected, a zoom sequence of 1 or 2 indicates the conditionwhere the zoom pulses are being counted, a zoom sequence of 3 indicatesthe activation of the reverse rotation brake, a zoom sequence of 4indicates the short-circuit braking condition, and a zoom sequence of 5indicates the open terminal condition (inactive condition) and thus theending of the series of the zoom drive sequences.

The AF Two-stage Extension Process!

FIG. 58 shows a flow chart for the AF two-stage extension process. TheAF two-stage extension process is executed when the focal length of thelenses has been changed and is the process in which the rear lens groupL2 is extended by a predetermined amount (AP1) from the AF home positionwhen the lenses are positioned at the "wide" side.

When the AF two-stage extension process is called, at step S3801, theCPU 210 judges whether or not the rear lens group L2 is presently in thecondition where it has been extended by a predetermined amount by the AFtwo-stage extension process. In the latest execution of the AF two-stageextension process, if the lenses were positioned at the "wide" end side(i.e., the zoom step was less than 4), the rear lens group L2 would havebeen extended by a predetermined amount and the two-stage extension flagwould have been set to 1. If the zoom step was 4 or more when theprevious AF two-stage extension process was executed, the rear lensgroup would not have been extended (would be positioned at the AF homeposition) and the two-stage extension flag would have been set to 0.

When the AF two-stage extension process is called with the two-stageextension flag being set to 1 at step S3801, then at step S3805, the CPUjudges whether or not the zoom step corresponding to the present lensposition is greater than 4. If the zoom step is greater than 4, namelythe rear and the front lens groups L1 and L2 are at the "tele" side, atsteps S3807 and S3809, the AF return process is called to return thealready extended rear lens group L2 to the AF home position, and controlis returned upon clearing the two-stage extension flag, i.e., settingthe flag to 0. If the present zoom step is 4 or less, although the rearlens group L2 needs to be extended, since the rear lens group L2 hasalready been extended when the previous AF two-stage extension processwas executed, control is returned without executing any process.

If the two-stage extension flag is not 1 at step S3801, namely, if theflag is set to 0, this would mean that the rear lens group L2 waspositioned at the AF home position at the end of the previous AFtwo-stage extension process. In this case, at step S3803 the CPU 210judges whether or not the zoom step is 4 or less, and if the zoom stepis greater than 4 at step S3803, since it is not necessary to extend therear lens group L2, in other words, it is sufficient for the rear lensgroup L2 to remain at the AF home position, the extension of the rearlens group L2 is not executed, and control is returned. If the zoom stepis 4 or less, namely if the lenses are positioned at the "wide" side,the process of extending the rear lens group L2 is executed. However,process method will differ according to whether or not the lenses are atthe "wide" end.

At step S3811, it is judged whether or not the value of the zoom step is0, in other words, whether the lenses are positioned at the "wide" endposition. If the lenses are positioned at the "wide" end position, therear lens group driving motor 30 may be connected with the barrieropening device and is not connected to the rear lens group movingdevice. In other words, if the rear lens group driving motor 30 isdriven in the state where the lenses are positioned at the "wide" endposition, the rear lens group L2 may not be driven and theopening/closing of the barrier may be executed instead.

On the other hand, when the lenses are at the "tele" position, ratherthan at the "wide" position, the rear lens group driving motor 30 willalways be connected to the rear lens group moving device. Therefore,when the lenses are not positioned at the "wide" end, namely the zoomstep is not 0 at step S3811, the rear lens group L2 can be made toextend from the AF home position by an amount corresponding to the AFpulse number AP1 by setting the predetermined value AP1 at the AF pulsecounter (step S3823) and calling the AF drive process at step S3825.After extending the rear lens group L2, the CPU 210 sets the two-stageextension flag to 1, and control is returned.

When the value of the zoom step is 0, namely when the lenses arepositioned at the "wide" end at step S3811, as already described, apossibility exists that the rear lens group driving motor 30 may beconnected to the barrier opening device. However, as long as the AFtwo-stage extension process is called during the lens return process,the rear lens group driving motor 30 is guaranteed to be connected withthe rear lens group moving device. Therefore at step S3813, the processis branched according to the zoom return flag, which indicates whetheror not the AF two-stage extension process being executed was called inthe lens return process. If the present AF two-stage extension processwas called in the lens return process, the zoom return flag would be setto 1. In such a case, at step S3823 and step S3825, only the driving ofthe rear lens group L2 is executed.

On the other hand, if the present AF two-stage extension process wascalled from a process other than the lens return process, the zoomreturn flag would be set to 0, and the CPU 210 will therefore executethe processes from step S3815.

At steps S3815 and S3817, the CPU 210 sets the predetermined values ZP1and AP1 respectively in the zoom pulse counter and the AF pulse counter,and at step S3819 the lens driving process is called, and the front andrear lens groups L1 and L2 are firstly moved by an amount correspondingto the zoom pulse ZP1, by driving the whole unit driving motor 30, andsimultaneously the rear lens L2 is moved by an amount corresponding tothe AF pulse AP1, by driving the rear lens group driving motor 30. Afterthat, in the zoom return process at step S3821, the front and the rearlens groups L1 and L2 are returned by an amount corresponding to thevalue ZP1, by driving the whole unit driving motor 25. That is, thelenses are once moved to the "tele" position by the predetermined amountso that the rear lens group driving motor 30 is surely engaged with thedriving device of the rear lens group L2, the rear lens group L2 isextended by driving the rear lens group driving motor 30, and afterthat, by returning the front and rear lenses toward the "wide" positionby the predetermined amount, eventually the rear lens group L2 is onlymoved toward the "wide" position.

As described above, at the point at which the AF two-stage extensionprocess is ended, if the lenses are at the "wide" position (i.e., thezoom step is not more than 4), the rear lens group L2 would be extendedby a predetermined amount and the two-stage extension flag would be setto 1. If the lenses are at the "tele" position (i.e., the zoom step isgreater than 4), the rear lens group L2 would be positioned at the AFhome position, and the two-stage extension flag would be set 0.

The Zoom Return Process!

FIG. 59 shows a flow chart for the zoom return process. The zoom returnprocess is the process in which the front lens group L1 and the rearlens group L2 are returned to the standby position at which they werepositioned prior to being moved in the lens driving process in thephotographing process. In other words, in this process the whole unitdriving motor 25 is driven in reverse (counterclockwise) by an amountcorresponding to the second zoom pulse ZP2 from the switching point atthe housed side of the present zoom code, in order to return the frontlens group L1 and the rear lens group L2 to the standby position, and isthen stopped upon being rotated forward (clockwise) by an amountcorresponding to the third zoom pulse ZP3, to eliminate backlash to somedegree, as shown in FIG. 34, i.e., the lens driving.

In the zoom return process at steps S3901, S3905, S3907, S3909 andS3911, it is checked whether or not the pulse number stored in the zoompulse memory is less than the first zoom pulse value ZP1, and if itless, the whole unit driving motor 25 is driven forward (clockwise),namely driven for movement in the tele direction. Then the value of thepulse, obtained by deducting the drive pulse value stored in the zoompulse memory from the first zoom pulse value ZP1, is set in the zoompulse counter, and the zoom pulse counting process is executed to waituntil the value of the zoom pulse counter becomes 0. When the valuebecomes 0, namely when the whole unit driving motor has been driven byan amount corresponding to the value of the first zoom pulse ZP1 fromthe switching point of the present zoom code, the whole unit drivingmotor 25 is stopped. In such a process, when the lenses are stoppedaround the "tele" position switching point of the present zoom code, thezoom code may become unstable during the initial stages of passingcurrent to the whole unit driving motor 25, and the standby position mayshift. For the purpose of avoiding such an occurrence, the whole unitdriving motor 25 is driven forward (clockwise) by an amountcorresponding to the value of the first zoom pulse ZP1 so that the zoomcode will definitely turn OFF. Then at step S3913, if the error flag isset to 1, control is returned, and if the error flag is not set to 1control proceeds to step S3915.

If the drive pulse number stored in the zoom pulse memory equals thefirst zoom pulse number ZP1, since this means that the lenses havealready been moved to the position at which the present zoom code turnsOFF, the process of driving the whole unit driving motor 25 is skipped.

At step S3915, the whole unit driving motor 25 is driven in reverse(counterclockwise), namely, driven for movement in the "wide" direction.Then at steps S3917, S3919, S3923 and S3929, the zoom code input processis called to detect the zoom code, and it is checked whether the "wide"code is detected, whether the housing code is detected, and whether thepresent zoom code is detected. If the "wide" code was detected, the lens"wide" position is set, while if the housed condition is detected, thewhole unit driving motor 25 is stopped and control is returned afterexecuting the lens extension process (steps S3919, S3921 and S3923, orat steps S3923, S3925 and S3927).

If the present zoom code is detected at step S3929, then at step S3931the zoom code input process is executed. Waiting is then performed untilthe OFF code is detected, namely, until the present zoom code turns OFF(step S3933). When the OFF code is detected, the second zoom pulse valueZP2 is set at the zoom pulse counter and the zoom pulse counting processis called to perform waiting until the value at the zoom pulse counterbecomes 0 (steps S3935, S3937).

At step S3939, upon returning from the zoom pulse counting process, thewhole unit driving motor 25 is stopped. At steps S3941, S3943, S3945 andS3947, if the error flag was set to 1, namely, if the return wasperformed without the value at the zoom pulse counter becoming 0,control is returned without executing any process. While if the errorflag was not set, the whole unit driving motor 25 is driven in a forward(clockwise) direction, the backlash elimination pulse number ZP3 is setat the zoom pulse counter, and the zoom pulse counting process is calledto wait for the value at the zoom pulse counter to become 0. Then atstep S3949, upon returning from the zoom pulse counting process, thewhole unit driving motor 25 is stopped and control is returned.

Thus by the zoom return process, the front lens group L1 is movedrearwardly to the standby position, which is retracted by the value ofthe second zoom pulse ZP2 from the rear end edge of the present zoomcode. At the standby position, backlash during a rotation of the wholeunit driving motor 25 in the "tele" direction is substantially removed.

The Zoom Standby Confirmation Process!

FIG. 60 shows a flow chart for the zoom standby confirmation process.The zoom standby confirmation process is the process called in thephotographing process, in which, when the photometering switch SWS isON, it is confirmed whether or not the lenses are positioned at thecorrect standby position, and if the lenses are not at the correctstandby position, the lenses are moved to the correct standby position.The processes after step S3931 of the zoom standby confirmation process,are the same as those of the zoom return process.

In the zoom standby confirmation process, at steps S4001 and S4003, thezoom code input process is called and the zoom code is input, and if thepresent zoom code is not detected, control is returned since it isassumed that the lenses are at the correct standby position. If thepresent zoom code is detected at step S4003, since this means that thelenses have moved from the standby position, at step S4005, the wholeunit driving motor 25 is driven in reverse (counterclockwise), namelydriven in the direction for movement to the "wide" side, and controlproceeds to step S3931, and the zoom code input process is executed.

The detection of the OFF code is then waited for and when the OFF codeis detected, the second zoom pulse number ZP2 is set in the zoom pulsecounter, and the zoom pulse counting process is called to wait for thevalue at the zoom pulse counter to become 0 (steps S3933, S3935 andS3937).

At step S3939, upon returning from the zoom pulse counting process, thewhole unit driving motor 25 is stopped. At steps S3941, S3943, S3945 andS3947, if the error flag was set to 1, namely if control was returnedwithout the value at the zoom pulse counter becoming 0, the control isreturned without executing any process. While if the error flag was notset, the whole unit driving motor 25 is driven in a forward (clockwise)direction, the backlash elimination pulse number ZP3 is set at the zoompulse counter, and the zoom pulse counting process is called to wait forthe value at the zoom pulse counter to become 0. Then at step S3949,upon returning from the zoom pulse counting process, the whole unitdriving motor 25 is stopped and control is returned.

As above described, in the zoom standby confirmation process, the frontlens group L1 and the rear lens group L2 are moved to the standbyposition, which is retracted by a predetermined distance from theswitching position at the "wide" side of the present zoom code, when thepresent zoom code corresponding to the zoom step is detected.

The Photographing Charging Process!

FIG. 61 shows a flow chart for the photographing charging process. Thephotographing charging process is the process executed when thephotometering switch SWS is ON, and is the charging process called whenit is judged in the photographing process that strobe flashing isnecessary.

When the photographing charging process is called, at step S4101 the CPU210 judges whether or not the charge disable timer is set to 0. Thecharge disable timer is the timer that times the period during whichcharging is disabled and a charge time of three seconds is set at thistimer when the flash capacitor 530 of the strobe device 231 becomesfully charged in the main charging process shown in FIG. 41. In such amanner, if the time of the charge disable timer is not up (i.e., thetimer value is not 0), although the charging of the flash capacitor 530will be disabled, strobe flashing will be enabled since the capacitor530 is almost fully charged. Therefore if the time is not up at thecharge disable timer at step S4101, then at step S4103 the charge-OKflag is set to 1 to indicate that the strobe can be flashed, and at stepS4104 the charging demand flag is set to 0, and control is returned uponending the photographing charging process.

The time will not be up at the charge disable timer at step S4101, ifthe strobe device 231 is not fully charged or if three or more secondshave passed since the strobe device 231 was fully charged. In suchcases, since charging is not disabled, and the CPU 210 sets thecharge-OK flag to 0 at step S4102, and the processes for charging afterstep S4105 are executed.

At step S4105, the CPU 210 judges whether or not the charge interruptionflag is set to 1. When a switch operation is performed while the maincharging process is being executed, the charging process is interruptedand the process corresponding to the operated switch is executed, and inthis process the charge interruption flag is set to 1.

If the charge interruption flag is set to 0, that is if the maincharging process was not interrupted at step S4105, a predeterminedlimit time (8 seconds) is set at the charging timer in order to restrictthe charging time. If the charge interruption flag is set to 1 at stepS4105, since the charging will be resumed, the charge interruption flagis cleared (set to 0) and the amount of the charge limiting timeremaining at the point at which charging was interrupted is set at thecharging timer (steps S4107 and S4109). In such a manner, even ifcharging is interrupted, a part of the predetermined charging limit time(8 seconds) will already have been spent in charging in the chargingprocess prior to the interruption. Since the charging time for thecharging process after interruption is set to the part of thepredetermined charging limit time (8 seconds) remaining after the abovementioned spent time, charging will have been performed for thepredetermined charging time when the charging is ended with the timebecoming up at the timer.

After the charging timer is set at step S4111 or S4109, the CPU 210 setsthe red lamp blinking flag to 1, and the red lamp 227 is blinked.Although the charging of the strobe flash capacitor 530 is executed inthe main charging process, without being recognized thereof by thephotographer, since the charging in the photographing charging processis executed while the photographer is pressing the shutter button 217halfway down, it is preferred to notify the photographer that chargingis in progress. For this purpose, in the photographing charging process,the red lamp 227 is blinked so that the photographer may recognize thatcharging is in progress.

When the charging timer is set, at step S4115 the charging signal is setto ON, namely the level at the terminal CHEN of the strobe device 231 isset to be H, and charging is started. The output of the terminal RLS ofthe strobe device 231, which corresponds to the charging voltage, isinput to the CPU 210 upon undergoing the A/D conversion. At step S4117the CPU 210 checks the A/D converted charging voltage. If the chargingvoltage has reached the level enabling strobe flashing at step S4119,then at step S4121 the CPU 210 sets the charge-OK flag to 1 to indicatethat strobe flashing is enabled, and at step S4123 the charging isstopped by setting the level at the terminal CHEN of the strobe circuit500 to low (L), and at step S4125 the red lamp blinking flag is set to0, and the blinking of the red lamp is stopped. In such a manner, thephotographer may recognize that the charging process is complete, namelythat the condition is no longer that in which the strobe cannot beflashed, in other words, photographing is now possible.

At step S4119, if the CPU 210 judges that the charging voltage has notreached the value enabling strobe flashing, then at step S4127 it isjudged whether or not the time at the charging timer is up. If the timeat the charging timer is up, then at step S4123 the level at theterminal CHEN of the strobe circuit 500 is set to low (L) to stopcharging, and at step S4125 the red lamp blinking flag is set to 0 toend the blinking of the red lamp. If the time is up at step S4127, thecharge-OK flag will not be set to 1, since the charging voltage will nothave reached the level at which flashing is enabled.

If the time of the charging timer is not up at step S4127, then at stepS4129 the CPU 210 judges whether or not the photometering switch SWS isOFF. If the photometering switch SWS is ON, the processes from stepsS4117 through S4127 are repeated. In such a manner, as long as theshutter button 217 is at least pressed halfway, charging is executeduntil the charging voltage reaches the level enabling flashing or untilthe charging time (eight seconds) has elapsed.

At step S4129, if the photometering switch SWS is judged to be OFF,namely if the half-pressed condition of the shutter button is canceledduring charging, then at step S4131 the CPU 210 makes the chargingsignal OFF, namely the CPU 210 turns OFF the charging signal, i.e., setsthe level at the terminal CHEN of the strobe circuit 500 to low, and atstep S4133 the remaining time, indicated by the charging timer, isstored in the memory, and at step S4135 the charge interruption flag isset to 1 to indicate that the charging has been interrupted. Then inorder to resume the execution of the remaining charging process canceledin the main charging process, at step S4137 the charging demand flag isset to 1, and then at step S4139 the red lamp blinking flag is set 0 tostop the blinking of the red lamp 227, and the photographing chargingprocess is ended. As above described, the remaining time stored in thememory at step S4133, and the charge interruption flag and the chargingdemand flag, are referenced during the execution of the main chargingprocess.

The Focusing Process!

FIG. 62 shows a flow chart for the focusing process. In the focusingprocess, the whole unit driving motor 25 is driven forward (clockwise)(i.e., in the direction in which the lenses are extended), and the rearlens group driving motor 30 is driven forward (clockwise) (i.e., in theretracting direction in which the rear lens group L2 is retracted) basedon the whole unit driving motor drive pulse number and the rear lensgroup driving motor drive pulse number calculated in the lens drivecalculation process, to thereby move the front lens group L1 and therear lens group L2 to the focused position, (see lens drive of FIG. 34).The present focusing process is characterized in that both the wholeunit driving motor 25 and the rear lens group driving motor 30 aredriven at the same time, i.e., driven in parallel.

In the focusing process, the zoom pulse counter value, namely, thenumber of pulses, calculated in the lens drive calculation process, bywhich the whole unit driving motor 25 is driven from the switching pointat the housed side of the present zoom code, is written into of the zoompulse memory at step S4201. The zoom sequence is then set to 0, and thewhole unit driving motor 25 is driven forward (clockwise), and thedriving check process is executed to wait for the zoom sequence tobecome 1, namely for the present zoom code to be detected (i.e., turnedfrom OFF to ON), and when the zoom sequence becomes 1, the AF sequenceis set to 0 (steps S4203, S4205, S4207, S4209 and S4211).

The rear lens group driving motor 30 is then driven forward (clockwise),and it is checked whether or not the value at the AF pulse counter isless than 50. If the value is less than 50, the control of the rear lensgroup driving motor 30 is changed to low-speed control (i.e., pulsewidth modulation (PWM) controlling), while if the value is not less than50, control proceeds to the zoom drive check process (steps S4213,S4215, S4217 and S4219, or at steps S4213, S4215 and S4219).

Waiting is then performed for both the zoom sequence and the AF sequenceto become 5, and when both become 5, namely when both the whole unitdriving motor 25 and the rear lens group driving motor 30 stop, controlis returned (steps S4219, S4221, S4223 and S4225).

In the focusing process, since both the whole unit driving motor 25 andthe rear lens group driving motor 30 are driven at the same time, thetime required for focusing by moving the front lens group L1 and therear lens group L2 to the focused position is shortened.

The Exposure Process!

FIGS. 63 through 65 show a flow chart for the exposure process. Theexposure process is called, namely executed, when the release switch SWRis turned ON. In the exposure process, the compensation process inregard to the shutter, and the shutter initial position confirmationprocess, etc., are executed, and the shutter is thereafter released toperform exposure.

Firstly, whether or not the AE adjustment has finished is checked, andif the AE adjustment has not finished or if the AE data is less than 10Ev even if the AE adjustment has finished, the AE timer time is selectedfrom among the fixed data stored in the ROM based on the AE dataobtained during the AE calculation process (steps S4301 and S4305, or atS4301, steps S4303 and S4305). If the AE adjustment has finished and theAE data is 10 Ev or more, at steps S4301, S4303 and S4307, based on theAE data obtained during the AE calculation process, the AE timer time isdetermined from among the adjustment data read during the reset process.The fixed data in the ROM is used when the AE data is less than 10 Evsince the shutter release time will be long when the AE data is lessthan 10 Ev and the influence of errors will therefore be small, andsince the process can be executed in a shorter time by using the data inthe ROM.

Then at steps S4309 and S4311, or at steps S4309 and S4313, whether theFM adjustment has completed or not is checked. If the FM adjustment hasnot completed, the FM timer time is selected from among the fixed datain the ROM based on the FM data, while if the FM adjustment hascompleted, the data that was read in the adjustment data reading processduring the reset process is used.

When the setting of the timers is completed, at steps S4315, S4317,S4319 and S4321, the shutter initial position confirmation process isexecuted. In the process, namely at steps S4315, S4317, S4319 and S4321,the AE motor 29 is driven in reverse (counterclockwise) to drive theshutter blades 27a in the shutting direction, the AE pulse countinglimit timer is started, and the AE pulse counting process is executed towait until the timer time is up. When the shutter blades 27a arecompletely shut, and become immovable, the time becomes up since the AEmotor 29 becomes incapable of rotating.

When the time is up, at steps S4323 and S4325, the AE motor 29 is drivenforward (clockwise) and the shutter is driven in the opening direction,and the AE pulse counting limit timer time is started. Then at stepsS4327, S4329 and S4331, the AE pulse counting process is executed andwaiting is performed until the reference pulse number is counted up inthe AE pulse counting process, while checking whether or not the time isup at the AE pulse counting limit timer time.

At steps S4329, S4333 and S4335, if the time becomes up at the AE pulsecounting limit timer time, it means that the rotation of the AE motor 29is impeded due to some reason, the shutter error flag is set, the AEmotor 29 is freed, namely the passage of current is stopped, and controlis returned.

At the moment when the counting of the reference pulse is ended, sincethe shutter blades 27a start to be opened. the AE timer and the FM timerare started, and the end-of-flash flag is cleared (steps S4335, 4337,S4339 and S4341).

Although it is checked whether or not the end-of-flash flag is set, andwhether or not the flash mode is set, in the case where the strobe isnot to be flashed, since the end-of-flash flag will remain cleared andthe flash mode will not be set, waiting is performed for the time to beup at the AE timer (steps S4343, S4345 and S4347).

When the time of the AE timer is up and if the bulb mode is not set, theAE motor 29 is driven in reverse (counterclockwise) (i.e., in thedirection in which the shutter is closed) to start the shutter bladeshutting operation and the AE pulse counting limit timer time is started(steps S4371 and S4373). Then while executing the AE pulse countingprocess, waiting is performed for the time to be up at the AE pulsecounter, namely, that the shutter blades 27a are shut and the AE motor29 is stopped, and when the time is up, the AE motor is freed, andcontrol is returned (steps S4375, S4377 and S4379). In the case of thebulb mode, the AE motor 29 is freed while the photometering switch SWSis ON, in order to prevent the AE motor 29 from overloading, and waitingis performed for the photometering switch SWS to be turned OFF (stepsS4365, S4367 and S4369).

If the strobe flashing mode is set, since this means that a flashingmode is set, control proceeds to step S4349, and it is checked whetheror not flashing is in progress, and since flashing will not be inprogress initially, waiting is performed for the time to be up at the FMtimer (steps S4349, S4351, S4347, S4313 and S4345). Since the FM timertime is normally shorter than the AE timer time, the time will normallybe up at the FM timer first. When the time is up at the FM timer,flashing is started and the 2 ms timer is started (steps S4351, S4353and S4355). The 2 ms timer is a timer for waiting for the completeending of the flashing of the strobe, and this waiting time is notlimited to 2 ms and may differ according to the characteristics of thestrobe.

When flashing is started, since flashing will be in progress, waiting isperformed until the time is up at the 2 ms timer (steps S4349, S4357,S4347, S4343 and S4345). When the time of the 2 ms timer is up, theflashing is stopped, the end-of-flash flag is set, and the chargingdemand flag is set (steps S4357, S4359, S4361 and S4363). Then at stepsS4343 and S4347, since the end-of-flash flag has already been set,waiting is performed until the time is up at the AE timer.

The Lens Return Process!

FIG. 66 shows a flow chart for the lens return process. The lens returnprocess is a process in which the front lens group L1 and the rear lensgroup L2, which been moved to the focused positions during thephotographing process, are returned to the positions prior to thephotographing process. The front lens group L1 is returned to thestandby position, retracted in the direction of the housing position byan amount corresponding to the second zoom pulse ZP2 from the "wide"side switching point of the zoom code corresponding to the zoom stepwhich identifies the present focal length. The rear lens group L2 isreturned to the AF home position if the zoom step is 5 or greater, ormoved to a position extended (i.e., retracted) from the AF home positionby an amount corresponding to the value of the AF pulse AP1, when thezoom step is between 0 and 4.

Firstly, in the lens return process, the AF return process is called,the rear lens group L2 is returned to the AF home position, and the lensreturn flag is set. Then the AF two-stage extension process is called,and if the zoom code is 5 or greater, the rear lens group L2 is left asit is. If the zoom code is 4 or less, the rear lens group L2 is extended(i.e., retracted) by an amount corresponding to the value of the APpulse AP1, and then the zoom return flag is cleared, i.e., set to 0.Then the zoom return process is called, and the front lens group L1 ismoved to the standby position of the present zoom code, and control isreturned (steps S4401, S4403, S4405, S4407 and S4409).

The Lens Drive Calculation Process!

FIG. 67 shows a flow chart for the lens drive calculation process. Thelens drive calculation process is the process in which the pulsenumbers, by which the whole unit driving motor 25 and the rear lensgroup driving motor 30 are to be driven, are determined based on thesubject distance (or the photographing distance) obtained in thefocusing processing and the present zoom step, as the zoom pulse numberfrom the "wide" side switching point (i.e., the ON/OFF point)corresponding to the present zoom step and the AF pulse value. In thefocusing process in the present embodiment, the direction in which thewhole unit driving motor 25 is driven is the direction in which thefront lens group L1 is advanced (extended), and the direction in whichthe rear lens group driving motor 30 is driven is the direction in whichthe rear lens group L2 is retracted from the AF home position, namely,moved away from the front lens group L1.

In the present embodiment, three modes of focusing are performed. At the"wide" end, whole focusing (first mode) is performed in which the frontlens group L1 and the rear lens group L2 are moved as a whole by thewhole unit driving motor 25. At the "tele" end, rear lens group focusing(third mode) is performed in which only the rear lens group L2 is movedby the rear lens group driving motor 30, and between the "wide" end andthe "tele" end, the front lens group focusing (second mode) is performedin which the front lens group L1 and the rear lens group L2 are moved bythe whole unit driving motor 25, and the rear lens group L2 is moved bythe rear lens group driving motor 30, so that the absolute position ofthe rear lens group L2 with respect to the camera will not be changed.

In the lens drive calculation process, at step S4501, the referenceamount of lens movement (i.e., the pulse number) 2T is calculated basedon the present zoom step and the subject distance obtained through thefocusing processing. Then at steps S4503, S4505, S4507, S4509, S4511,S4513 and S4515, it is judged whether the present zoom step is 0 (i.e.,the "wide" end), between 1 and 12 (i.e., intermediate position betweenthe "wide" end and the "tele" end), or 13 (i.e., the "tele" end), andthe pulse calculation process corresponding to the zoom step isexecuted. At steps S4505 and S4507, if the present zoom step is at the"wide" end, the whole focusing will be performed, and the value (a*ΔX2T)is set in the zoom pulse counter, and the value 0 is set in the AF pulsecounter. If the present zoom step corresponds to an intermediateposition, the front lens group focusing will be performed, and at stepsS4509 and S4511, the value (b*ΔX2T) is set in the zoom pulse counter,and the value (c*ΔX2T) is set in the AF pulse counter. If the presentzoom step corresponds to the "tele" end, the rear lens group focusingwill be performed, and at steps S4513 and S4515, the value 0 is set inthe zoom pulse counter, and the value (ΔX2T) is set in the AF pulsecounter. The symbols a, b, c and ΔX are predetermined compensationfactors.

When the setting of the pulse counter is complete, at step S4517, thecorrection value X2f, according to the focal length, is added to thevalue of the AF pulse counter. Then at steps S4519 and S4521, theadjustment data is read from the EEPROM 230, and are further added tothe values at the AF pulse counter and the zoom pulse counter. At stepsS4523 and S4525 it is checked whether or not the AF two-stage extensionflag is set, and if it is set, since the rear lens group L2 has alreadybeen extended (retracted) by the value of the AF pulse AP1 from the AFhome position, the value AP1 is deducted from the AF pulse counter.

In the above processing, the setting of the drive pulse number of thewhole unit driving motor 25 and the drive pulse number of the rear lensgroup driving motor 30, for moving the front lens group L1 and the rearlens group L2 to lens positions at which the lenses will be in focuswith the subject at the present focal length, are completed.

The Test Function Process!

FIG. 68 shows a flow chart for the test function process. The testfunction process is the process for testing the functions of the camera,and is called to execute the various functions of the camera with thecamera being connected to a measuring device.

In the prior art cases of performing tests upon connecting a measuringdevice to a camera, the commands to be input into the camera from themeasuring device are determined in advance and predetermined processesare executed at the camera side according to the various commands inputfrom the measuring device. However, when tests are performed by such amethod, only predetermined operations can be executed and otheroperations cannot be executed. Test operations can only be performed fortest items that are considered at the time of preparation of the programand test items cannot be added later. With the camera of the presentembodiment, programs for controlling the camera can be designed onefunction at a time from the measuring device and caused to be executedby the camera.

The test function process is called during the reset process, when thereset process is executed. Therefore, the test function process isexecuted by connecting the measuring device (not shown) to the camera,when the battery is loaded into the camera.

When the test function process is called, at step S7101 a handshakebetween the CPU 210 of the camera and the measuring device, connected tothe camera, is executed, and the communication condition is set. If anerror occurs during the handshake, or if the measuring apparatus is notconnected to the camera, it is deemed that the handshake wasunsuccessful at step S7103, and the test function process is canceled,and control is returned. If the handshake is successful andcommunication is enabled at step S7103, the input of commands from themeasuring device to the CPU 210 is enabled (step S7105).

If the command data has a value 0, which indicates the end of the testfunction process at step S7107, control is returned upon ending the testfunction process. If the value of the command data is not 0, the upperaddress and the lower address of the function to be called are receivedthrough serial communication from the measuring device (steps S7109,S7111) and the function stored in the address is executed at step S7113.The processes related to the test items necessary, are executed byrepeating the above until the command data with a value of 0 isreceived.

As described above, detailed tests can be performed with the camera ofthe present embodiment, since the camera controlling programs can bedesigned and executed in function units by means of data input from themeasuring device.

The AF Pulse Counting Process!

FIG. 69 shows a flow chart for the AF pulse counting process. The AFpulse counting process is the process in which the priority set AF pulsecounter is decremented by one each time a change in the AF pulse isdetected within a predetermined time period, and the OK flag is set to 1when the value at the AF pulse counter becomes 0. The OK flag is set to0 if the value at the pulse counter does not become 0 within thepredetermined period.

At step S7201, the CPU 210 first sets a time of 200 ms at a timer as theperiod during which the changes in the AF pulse are to be monitored. Inthe following processes, if there is no change in the AF pulse within200 ms period, the CPU 210 sets the OK flag to 0, as above described.

At step S7203, the CPU 210 judges whether or not the time is up at the200 ms timer. If the time is not up, then at step S7207, whether or notthere was a change in the AF pulse is judged based on the output signalfrom the AF pulse input circuit 222 to the CPU 210. The judgment as towhether or not there is a change in the AF pulse is made by detectingthe change of the pulse from both H (high) level to L (low) level andvice versa.

If there is no change in the AF pulse at step S7207, the CPU 210 returnsthe process to step S7203. Therefore, if no changes in the AF pulse aredetected within the 200 ms, it is judged that the time is up at stepS7203, and the process is ended upon setting the OK flag to 0 at stepS7205. In other words, the OK flag is set to 0 if the same number ofpulses as the value set at the AF pulse counter before the AF pulsecounting process was called is not detected during the execution of theAF pulse counting process.

When the CPU 210 detects a change in the AF pulse at step S7207, then atstep S7209 the timer is reset, and the period of 200 ms is set again andrestarted. If the detected change in the AF pulse is a rise of the AFpulse at step S7211, then at step S7213 the AF pulse counter isdecremented by one. Here, the value to be counted, that is, the valuecorresponding to the amount by which the rear lens group L2 is to bedriven by the rear lens group driving motor 30, is set at the AF pulsecounter before the AF pulse counting process is executed. If the valueat the decremented AF pulse counter is 0 at step S7215, the CPU 210 setsthe OK flag to 1 and ends the process. That is, the OK flag is set to 1if the same number of pulses as the value set at the AF pulse counterbefore the AF pulse counting process was called has been counted.

As described above, in the AF pulse counting process, the OK flag is setto 1 if the same number of pulses as the value set previously at the AFpulse counter are output from the AF pulse input circuit 222 to the CPU210, and the OK flag is set to 0 if the output of pulses is stoppedbefore the AF pulse input circuit 222 outputs the same number of pulsesto the CPU 210 as the value set at the AF pulse counter.

The Zoom Drive Check Process!

FIG. 70 shows a flow chart for the zoom drive check process. Inaddition, the relationship between the driving state of the whole unitdriving motor 25 and the zoom sequence is shown in the form of a timingchart in FIG. 35. The zoom drive check process is a process in which itis judged at which stage the driving of the lenses by the whole unitdriving motor 25 for focusing on the subject distance is at, and inwhich stage the driving control of the whole unit driving motor 25 iscarried out.

When the zoom drive check process is executed, according to the value ofthe zoom sequence (0 through 5), which is the index that indicates thestate of driving of the whole unit driving motor 25, namely, the stateof operation of the whole unit driving motor controlling circuit 60, theprocess branches at step S7301. When the zoom drive check process iscalled, the condition will be one in which the whole unit driving motor25 is driven forward (clockwise), and the zoom sequence is set to 0.

At step S7303, if the value of the zoom sequence is 0, the CPU 210 callsthe zoom code input process, and the value of the zoom code is input.When the lenses are stopped, the terminal for zoom code detection ispositioned to the "wide" side of the zoom code. When the whole unitdriving motor 25 is driven forward (clockwise), the zoom code detectionterminal first contacts the zoom code corresponding to the preset lensposition. If the zoom code input in the zoom code input process equalsto the value stored in the memory as the present zoom code at stepS7305, then at step S7307 the zoom sequence is set to 1. If the zoomcode set in the zoom code input process differs from the value stored inmemory as the present zoom code at step S7305, the zoom sequence remainsat 0, and the zoom drive check process is ended.

When the value of the zoom sequence is 1, namely, after the present zoomcode is detected, at step S7311 the CPU 210 monitors the rise of thezoom pulse output by the zoom pulse input circuit 220. At steps S7311and S7313, the zoom pulse is then only decremented if the rise of thezoom pulse is detected. When the zoom pulse counter becomes less than 20at step S7315, then at step S7317 the CPU 210 switches the whole unitdriving motor 25 to the low-speed control, and at step S7319, the valueof the zoom sequence is set at 2. If the value at the zoom pulse counteris equal to or greater than 20 at step S7315, the zoom sequence remainsat 1, and the zoom drive check process is ended.

Therefore, when the whole unit driving motor 25 is started to drive, thezoom pulse counter is decremented on the basis of the present zoom code,and according to the pulses output by the zoom pulse input circuit 220to the CPU 210. The whole unit driving motor 25 is driven by the normalDC drive until the count at the zoom pulse counter becomes 20. The zoomsequence will be 1 while the whole unit driving motor 25 is being drivenat normal speed. If the driving in the DC drive condition is continued,the lenses may be moved by more than the amount corresponding to thedesired number of pulses due to inertia, etc., when the whole unitdriving motor 25 stops. Therefore, when the zoom pulse counter becomesless than 20, the whole unit driving motor 25 is put under low speedcontrol. The low-speed control is executed by means of PWM control. Whenthe driving of the whole unit driving motor 25 is switched to low-speedcontrol, the zoom sequence is set to 2.

When the zoom sequence is 2, namely during the low-speed control of thewhole unit driving motor 25, if the zoom drive check process is called,the processes from step S7321 are executed. In such processes, at stepS7321 the CPU monitors a rise of the zoom pulse, and decrements the zoompulse when a rise is detected at step S7323. If a rise of the zoom pulseis not detected at step S7321, the process at step S7323 is skipped.

Until the zoom pulse count, which is decremented by one at a time whilethe lenses are being driven with the whole unit driving motor 25 beingunder low-speed control, become 0, the processes at steps S7321 andS7323 are executed each time the zoom drive check process is called. Thezoom sequence will remain at 2 during this period. When the zoom pulsebecomes 0 at step S7325, the whole unit driving motor 25 is driven inreverse (counterclockwise) at step S7327, to perform the braking process(i.e., reverse brake). After starting the reverse (counterclockwise)driving of the whole unit driving motor 25, at step S7328, the time of 5ms, which is the reverse driving period, is set at the timer, and thezoom sequence is set to 3 at step S7329. In such a manner, when the zoomsequence is 3, the whole unit driving motor 25 is driven in reverse(counterclockwise) for braking.

When the zoom sequence is 3, if the zoom drive check process is called,at step S7331 the CPU 210 judges whether the period of 5 ms, which isthe period of the reverse (counterclockwise) driving of the whole unitdriving motor 25, has elapsed or not. If 5 ms has not elapsed, controlis returned with the zoom sequence remaining at 3. After 5 ms haveelapsed, at steps S7333, S7335 and S7337, braking is performed byshort-circuiting the terminals of the whole unit driving motor 25, andthe 20 ms timer is started, and the zoom sequence is set to 4, andcontrol is returned.

If the zoom driving check processing is called when the zoom sequence is4, at step S7341 the CPU 210 monitors whether or not the zoom pulsechanges. That is, whether or not the whole unit driving motor 25 isrotating under the condition where the brakes are acting is judgedaccording to whether or not the zoom pulse changes within 20 ms.

If the CPU 210 judges, that there is no change in the zoom pulse at stepS7341, and that the time is up at the 20 ms timer at step S7345, then atsteps S7347 and S7349, the control of the whole unit driving motor 25 isstopped, and the terminals of the motor are brought in to the opencondition (i.e., undriven condition), and the zoom sequence is set at 5.If it is detected at step S7341 that the zoom pulse has changed, the 20ms timer is restarted at step S7343, and it is monitored whether or notthe next change in the zoom pulse is detected within the 20 ms after theprevious change in the zoom pulse. A return is performed with the brakeacting on the whole unit driving motor 25 and with the zoom sequenceremaining at 4 until it is judged at step S7345 that the time is up atthe 20 ms timer.

If the zoom drive check process is called when the zoom sequence is 5,as shown in the flow chart, control is returned without executing anyprocesses in the zoom drive check process.

As above described, in the zoom drive check process, the lenses arefirstly moved to the position of the present zoom code, which is thereference position (zoom sequence=0). The lenses are then moved at thenormal speed while the counter at the zoom pulse counter is 20 or more(zoom sequence=1), and then moved at a low speed when the count at thezoom pulse counter becomes less than 20 (zoom sequence=2). When thecount at the zoom pulse counter becomes 0, the whole unit driving motor25 is driven in reverse (counterclockwise) for 5 ms (zoom sequence=3),and thereafter, braking is performed by making the terminals of thewhole unit driving motor 25 short-circuit (zoom sequence=4). When thewhole unit driving motor 25 comes to a complete stop, its control isended (zoom sequence=5), and thereafter, the whole unit driving motor 25is not controlled, namely, the undriven condition is maintained, until anew value is set at the zoom pulse counter and the zoom sequence is setto 0.

The AF Drive Process!

FIG. 71 shows a flow chart for the AF drive process. The AF driveprocess is a process in which the rear lens group motor 30 is driven andcontrolled so as to move the rear lens group rearwardly, i.e., towardsthe film plane, in the lens retracting direction, in which the rear lensgroup L2 is moved rearwardly in order to set the focus on the subjectdistance.

At step S7401 the AF sequence is first set to 0. At steps S7403 andS7405 the rear lens group driving motor 30 is driven forward(clockwise), namely, driven in the retracting direction, and it ischecked whether or not the count at the AF pulse counter is less than50. If the count is less than 50, the control of the rear lens groupdriving motor 30 is switched to low-speed control (i.e., the PWMcontrol), while if the count is 50 or greater, the AF drive checkprocess is called without switching the control (steps S7405, S7407 andS7409, or at steps S7405 and S7409). Then at steps S7409 and S7411, itis then waited for the AF sequence to become 5 while performing the AFdrive check process and a return is performed when the sequence becomes5.

The AF sequence is an identifier which identifies the state of theoperation sequence of the rear lens group driving motor controllingcircuit 61, and as shown in FIG. 35 and FIG. 36, an AF sequence of 0indicates the condition where the switching of the AF home signal, basisfor the counting of AF pulses, has been detected, 1 and 2 indicate thecondition in which the AF pulses are being counted with 1 indicating theDC drive condition and 2 indicating the low-speed control condition, 3indicates the reverse braking condition, 4 indicates the short-circuitbraking condition, and 5 indicates the open terminal condition(inactivated condition) and thus the ending of the series of sequences.

If the rear lens group driving motor 30 is driven by the DC drive whenthe AF pulse number by which the rear group moving motor 30 is to bedriven is small, the rear lens group driving motor 30 may be driven, dueto inertia, etc., by more than the AF pulse number by which it issupposed to be driven. Thus when the AF pulse number is less than 50,the start-up and driving are performed from the beginning at the samelow speed as in AF sequence 2.

The Zoom Pulse Counting Process!

FIG. 72 shows a flow chart for the zoom pulse counting process. The zoompulse counting process is a process in which the previously set zoompulse counter is decremented by one each time a change in the zoom pulseoutput from the zoom pulse input circuit 220, is detected within apredetermined period, and which is ended when the count at the zoompulse counter becomes 0. If a change in the zoom pulse is not detectedwithin the above-mentioned predetermined period, the error flag is setto 1.

At step S7501, the CPU 210 first sets the period of 200 ms at the timeras the period during which the change in the zoom pulse is to bemonitored. In the following processes, if there is no change in the zoompulse within 200 ms, the CPU 210 sets the error flag to 1.

At step S7503, the CPU 210 judges whether or not the time is up at the200 ms timer. If the time is not up, then at step S7507, it is judgedwhether or not there was a change in the zoom pulse based on the outputpulse from the zoom pulse input circuit 220 to the CPU 210. Whether ornot the zoom pulse changed is judged here by detecting the change in thepulse both from the H (high) level to the L (low) level and vice versa.

If there is no change in the zoom pulse at step S7507, the CPU 210returns to the process at step S7503. Therefore, if the change in thezoom pulse is not detected within 200 ms, at step S7503 it is judgedthat the time is up, and at step S7505 the error flag is set to 1 andcontrol is returned. In other words, a return is performed upon settingthe error flag to 1, if the same number of pulses as the value set atthe zoom pulse counter before the zoom pulse counting process was calledis not detected within the interval during which the zoom pulse countingprocess is executed.

When the CPU 210 detects a change in the zoom pulse at step S7507, thenat step S7509 the timer is reset to 200 ms. If the detected change inthe zoom pulse is a rise of the zoom pulse at step S7511, then at stepS7513 the zoom pulse counter is decremented by one. Here, the value tobe counted, that is, the value corresponding to the amount by which thelenses are to be driven by means of the whole unit driving motor 25(i.e., the count of the pulses output by the zoom pulse input circuit220), is set at the zoom pulse counter before the zoom pulse countingprocess is executed. When the count at the decremented zoom pulsecounter becomes 0 at step S7515, the CPU 210 ends the process. That is,the process is ended normally if the same number of pulses as the valueset at the zoom pulse counter before the zoom pulse counting process wascalled has been counted.

As described above, in the zoom pulse counting process, a return isperformed without setting the error flag if the same number of pulses asthe value set previously at the zoom pulse counter are counted while areturn is performed upon setting the error flag to 1, if the same numberof pulses as the value set at the zoom pulse counter by the zoom pulseinput circuit 220 could not be counted.

The AF Drive Check Process!

FIG. 73 shows a flow chart for the AF drive check process. The AF drivecheck process is a process in which the rear lens group driving motor 30is controlled so that the rear lens group L2 will be driven based on thevalue set at the AF pulse counter.

Upon execution the AF drive check process branches at step S7601according to the value of the AF sequence (0 through 5), which is anidentifier that identifies the state of the operation sequence of therear lens group driving motor controlling circuit 61. When the AF drivecheck process is executed for the first time, the rear lens groupdriving motor 30 is driven, and the AF sequence is set to 0. FIG. 35shows the relationship between the driving state of the rear lens groupdriving motor 30 and the AF sequence.

At step S7603, if the value of the AF sequence is 0, the CPU 210 judgeswhether or not the AFH (i.e., the "AF home") signal has changed from H(high) to L (low). The AFH signal is H (high) when the rear lens groupL2 is positioned at the AF home position, and changes to L (low) whenthe rear lens group L2 moves away from the AF home position. Themovement of the rear lens group L2 based on the AF pulse counter,described below, is executed on the basis of the position at which theAFH signal changes to L. When the AFH signal changes from H to L at stepS7603, then at step S7605 the CPU 210 sets the AF sequence to 1, andcontrol is returned. While the AFH signal is H, control is returnedwhile the AF sequence remains at 0.

If the value of the AF sequence is 1, namely, after the change of theAFH signal from H to L is detected, at step S7611 the CPU 210 monitorsthe rise of the AF pulse. At steps S7611 and S7613, the AF pulse counteris decremented only when the rise of the AF pulse is detected, and whenthe count at the AF pulse counter becomes less than 200 at step S7615,then at step S7617 the CPU 210 switches the rear lens group drivingmotor 30 to low-speed control, and at step S7619, the value of the AFsequence is set to 2. If the AF pulse counter is 200 or more at stepS7615, the AF drive check process is ended and control is performed withthe AF sequence remaining at 1. If the DC drive of the rear lens groupdriving motor 30 is performed from the beginning to the end, the desiredAF pulse number may be exceeded due to the influence of inertia, etc.Thus, when the remaining AF pulse number becomes 200, the rear lensgroup driving motor 30 is driven at low speed through the PWM control.

As described above, when the rear lens group driving motor 30 is startedto drive, the AF pulse counter is decremented on the basis of the pointat which the AFH signal changes from H to L, and normal DC drive of therear lens group driving motor 30 is performed until the count at the AFpulse counter becomes 200. While the normal drive of the rear lens groupdriving motor 30 is being performed, the AF sequence will be 1. When thecount at the AF pulse counter becomes less than 200, the rear lens groupdriving motor 30 is driven under low-speed control. When the rear lensgroup driving motor 30 comes under low-speed control, the AF sequence isset to 2.

When the AF drive check process is called when the AF sequence is 2,that is, when the rear lens group driving motor 30 is under low-speedcontrol, the processes from step S7621 are executed. In such processes,at step S7621 the CPU 210 monitors the rise of the AF pulse, and if arise of the AF pulse is detected, at step S7623 the zoom pulse counteris decremented. If the rise of the AF pulse is not detected at stepS7621, the process at step S7623 is skipped.

Before the AF pulse count, which is decremented by one at a time whilethe rear lens group L2 is being driven with the rear lens group drivingmotor 30 being under low-speed control, becomes 0, the processes atsteps S7621 and S7623 are executed each time the AF drive check processis called. In such a case, the AF sequence will remain at 2. When the AFpulse count becomes 0, by driving the whole rear lens group drivingmotor 30 in reverse (counterclockwise) at step S7627, the brakingprocessing (i.e., reverse brake) is executed. After starting the reverse(counterclockwise) driving of the rear lens group driving motor 30, atstep S7628, the time of 5 ms, which is the reverse (counterclockwise)driving period, is set at the timer, and the AF sequence is set to 3 atstep S7629. In such a manner, when the AF sequence is 3, the rear lensgroup driving motor 30 is driven in reverse (counterclockwise) forbraking.

When the AF sequence is 3, if the AF driving check processing is called,at step S7631 the CPU 210 judges whether or not the period of 5 ms haselapsed, and if 5 ms has not elapsed control is returned with the AFsequence remaining at 3. After 5 ms has elapsed, then at step S7633,step S7635 and step S7637, the braking is activated by short-circuitingthe terminals of the rear lens group driving motor 30, and the 20 mstimer is started, and the AF sequence is set to 4, and control isreturned.

If the AF drive check process is called when the AF sequence is 4, atstep S7641 the CPU 210 monitors whether or not the AF pulse changes.That is, whether or not the rear lens group driving motor 30 is rotatingunder the condition where the brake is acting, is judged according towhether or not the AF pulse changes within 20 ms.

If the CPU 210 judges, that there is no change in the AF pulse at stepS7641, and that the time is up at the 20 ms timer at step S7645, atsteps S7647 and S7649, the control of the rear lens group driving motor30 is stopped, and the terminals of the motor are brought into the opencondition (i.e., undriven condition), and the AF sequence is set to 5.If the change of the AF pulse is detected at step S7641, the 20 ms timeris restarted at step S7643, and it is monitored whether or not the nextchange in the AF pulse is detected within 20 ms after the previouschange in the AF pulse. At step S7645, a return is performed with thebrake acting on the rear lens group driving motor 30 and with the AFsequence remaining at 4 until it is judged that the time is up at the 20ms timer.

If the AF drive check process is called when the AF sequence is 5, asshown in the flow chart, the control is returned without executing anyprocesses in the AF drive check process.

As above described, in the AF drive check process, the lenses arefirstly moved to the reference position at which the AFH signal becomesL (the AF sequence=0). The rear lens group is then moved by the normalDC drive while the count at the AF pulse counter is 200 or more (the AFsequence=1), and then moved at low speed by PWM when the count at the AFpulse counter becomes less than 200 (the AF sequence=2) When the countat the AF pulse counter becomes 0, the rear lens group driving motor 30is driven in reverse (counterclockwise) for 5 ms (the AF sequence=3),and thereafter, braking is performed by making the terminals of the rearlens group driving motor 30 short-circuit (the AF sequence=4). When therear lens group driving motor 30 comes to a complete stop, its controlis ended (the AF sequence=5), and thereafter, the rear lens groupdriving motor 30 is not controlled (undriven condition is entered),until a new value is set at the AF pulse counter and the AF sequence isset 0.

The exposure controlling device will be described hereinafter. Theoperation of a shutter of the present embodiment that is driven by a DCmotor is described first, the detection mechanism for detecting theoperation of the shutter and the shutter control method in the exposureprocess shall be described next, and the method for compensatingvariations due to individual mechanical differences among shutters shallbe described last.

The shutter 27 of the present embodiment functions to determine anexposure interval based on a determined shutter speed and also definesan aperture based on a determined aperture value. The shutter 27 isdriven by the AE motor 29 (a shutter driving motor), which is a DCmotor, and the aperture area of shutter 27 is determined as a timeperiod functionally related to the rotation of AE motor 29 from areference starting point where the shutter 27 is fully closed. Since therotation speed of the AE motor 29 can be taken as constant, the aperturearea can be univocally identified in response to the time period.

The shutter speed can also be determined as the driving time interval ofthe AE motor until its rotation is reversed. In particular, since theshutter is driven in the closing direction immediately after thediameter of the shutter reaches the required aperture area, except incase of full aperture exposure as the present embodiment, the shutterspeed and the aperture area are determined as combination based on thetime period. In the other words, shutter speed and aperture area are notdetermined independently. Additionally, since the combination of theshutter speed value Tv and the aperture value Av is determined based onthe exposure value Ev, the time period can be univocally determined withrespect to the exposure value Ev that is determined based on abrightness value Bv and a film speed Sv (i.e., Ev=Av+Tv=Bv+Sv).

When the object brightness is lower than a predetermined level and thecontrolling unit is set in the strobe emission mode, the aperture areaat which the strobe should be emitted is determined by a flashmatic (FM)calculation based on the object distance and the guide number of thestrobe. Since the camera of the present embodiment has a built-in strobeand the quantity (emission) of flash light can be considered asconstant, the guide number is fixed, and therefore, the aperture valueAv during flashing is determined as a function of the object distance.As described above, the aperture value Av is determined as the timeperiod, and the strobe flashes at the time when the time period iselapsed in the strobe emission mode.

As indicated in the above description of the flowcharts, the photographyprocess (FIG. 49) starts when it is detected that the photometry switchturns ON at S0051 of the main process (FIG. 41). And when it isdetermined that the release switch turns ON in S1719, the exposureprocess (FIGS. 63-65) is subsequently executed in S1731.

In the exposure process, the AE timer time and the FM timer time aredetermined first. The AE timer time defines the time period to determinethe aperture area in the strobe no-emission mode, and the FM timer timedefines the time period to determine the aperture area in the strobeemission mode.

The AE motor 29 rotates forward to open the shutter and changes arotating direction to reverse after the elapsing of the AE timer time.That is, the AE timer time defines the time period between the pointwhen the shutter is positioned at the reference starting point and thepoint where the rotating direction of the AE motor 28 is changed. In thestrobe no-emission mode, the AE timer time varies depending on theexposure value Ev.

In the flash emission mode, the AE timer time is set as thepredetermined constant value that is longer than the time required forfully opening the shutter. The AE motor 29 rotates forward to open theshutter and the flash emits after the FM timer time elapses when thecamera of the present embodiment is in the strobe emission mode. The AEmotor 29 is controlled to rotate reversely when the AE timer time iselapsed. The FM timer time defines the time period between the pointwhen the shutter is positioned at the reference starting point and thepoint when the strobe is flashed.

As shown in FIG. 74, the exposure controlling device of the embodimentis provided with an encoder as a pulse generator for generating pulsesas the shutter blades are driven. One of the pulses from the encoder isused for determining the reference starting point where the timers arestarted to count, and the other pulses are used for determining whetherthe shutter blades are normally driven.

An encoder comprises a photocoupler and a rotating disk positioned inconnection with the photocoupler. The photocoupler includes a lightemitting element such as a LED and a light receiving element such as aphotodiode. The rotating disk is provided with a first angular rangewhere the output signal from the photocoupler does not vary even whenthe rotating disk rotates and a second angular range where the outputsignal varies in cycles in accordance with the rotation of the rotatingdisk.

A light modulating pattern is applied to the second angular range. Thelight modulating pattern may be formed as a plurality of transparentparts arranged on the opaque surface or a plurality of light reflectingparts arranged on the low reflectivity surface. In case that thetransparent parts are formed, a photointerrupter should be used as aphotocoupler to detect the transmitted light through the transparentparts. On the other hand, when the light reflecting parts are formed, aphotoreflecter should be used to detect the reflected light from thelight reflecting parts.

In the encoder of the present embodiment, the photointerrupter 57 isused as the photocoupler and the rotating disk 59 has radially-orientedslits 59a that are angularly spaced. The rotating disk 59 rotatescorresponding to the actuation of the shutter 27 by less than one fullturn.

The slits 59a are formed at constant angular intervals along acircumferential direction formed except the portion where thephotointerrupter 57 detects when the shutter is fully closed. In thisembodiment eighteen slits 59a are formed at quiangular intervals over anangular range of approximately 270 degrees.

The photointerrupter 57 includes a light emitting element and lightreceiving element which face each other with a slot therebetween. Adetecting position 57a in FIG. 74 represents a position of the lightreceiving element. The rotating disk 59 is inserted in the slots of thephotointerrupter 57. The light receiving element of the photointerrupter57 detects the light emitted from the light emitting element andtransmitted through the slits 59a. The output of the light receivingelement is a LOW level when the light from the light emitting elementtransmits through the slit and is detected by the light receivingelement. The output of the light receiving element is a HIGH level whenthe transmitted light is interrupted by an opaque portion of therotation disk 59. As the rotating disk 59 rotates, the light receivingelement outputs the AE pulse signal, which is input to the AE motorcontrol circuit 66 by way of the control circuit 210.

The rotating disk 59 rotates in a counterclockwise direction in FIG. 74as the shutter 27 is driven to open and rotates in a clockwise directionas the shutter is driven to close. The motion of the shutter 27 ismechanically limited at both ends where the shutter blades are fullyclosed (closed end) and are fully opened (opened end). When the shutter27 is mechanically contacted at the closing end, the portion where theslits are not formed is located at the detecting position 57a of thephotointerrupter 57. FIG. 74 shows the condition where the rotating disk59 is located at the closed end that is a regular initial position ofthe rotating disk 59.

The output pulse signal from the photointerrupter 57 is input into thecontrolling circuit (CPU) 210. The controlling circuit 210 detects thereference start point of the shutter and confirms whether the AE motor29 rotates or not based on the AE pulse signal.

As described above, since the maximum rotation range of the rotatingdisk 59 is less than 360 degrees, i.e., it rotates by less than one fullturn, and since the light transmitting parts are not formed at theportion which corresponds to the photointerrupter 57 in the fully closedcondition of the shutter, the output signal in the fully closedcondition is always a HIGH level and therefore the controlling circuit210 can determine that the shutter is fully closed based on the outputof the photointerrupter 57 without moving the rotating disk 59.

Next, the operations of the exposure controlling device of the presentembodiment will be described with reference to the timing charts shownin FIGS. 75, 77 and 80 and the relationship between the rotating disk 59and the photointerrupter 57 shown in FIG. 76 78 and 79. FIGS. 75 and 79are timing charts for the strobe emission mode and FIG. 77 is a timingchart for the strobe no-emission mode.

As shown in FIG. 75, the CPU 210 controls the AE motor controllingcircuit 66 to apply a reverse rotation voltage to the AE motor 29 inorder to rotate the AE motor 29 in the reverse direction at point t1.The reverse rotation of the AE motor 29 is called at S4315 of FIG. 63.The shutter 27 is forced to rotate in reverse direction to contact atthe closed end. If the shutter 27 is positioned at the regular initialposition shown in FIG. 74 before the exposure, a pulse is not outputwhile the reverse voltage is applied between points t1 and t3 as shownin FIG. 75.

At the point t3 (S4323), the CPU 210 controls the AE motor controllingcircuit 66 to apply a forward rotation voltage to the AE motor 29 torotate in forward direction in order to open the shutter 27. The pointt3 is defined as a point when a period T_(WT) of the AE pulse countinglimit timer (S4317) has elapsed since the last rising edge of the AEpulse when the AE pulse output. When the AE pulse is not output (i.e.,LOW), the period T_(WT) is counted from the point t1 as shown in FIG.75. In accordance with the present embodiment, the period T_(WT) of theAE pulse counting limit timer is a period of time of sufficient lengthfor driving the shutter 27 to the closed end from the position where theslit 59a that is the most nearest to the closed end is detected by thephotointerrupter 57.

Since the shutter 27 is first set at the fully closed position and thenstarts to open, the shutter blades are always driven under constantconditions. That is, the operation of the shutter 27 is always performedunder the same conditions because the shutter 27 is driven in thereverse direction to a fully closed position, and the driven in theforward direction from the fully closed position, thus allowing the AEmotor 29 to obtain a stabilized condition.

As the AE motor 29 is driven in the forward direction to open theshutter, the rotating disk 59 rotates in the 10 counterclockwisedirection and the photointerrupter 57 generates AE pulse signals. In thepresent embodiment, the reference starting point is defined, forexample, as a rising edge of the third AE pulse t4 from the fully closedposition as shown in FIG. 75. The AE motor 29 is driven in forwarddirection until the AE timer time T_(AE) has elapsed from the point t4and then changes the rotating direction from forward to reverse at pointt5 (S4371) due to apply the reverse voltage. The AE timer time isdetermined at S4305 or S4307 depending upon the exposure value Ev, todefines the time period between the points t4 and t5.

During the forward rotation between the points t3 and t5, eleven AEpulses are output and the shutter 27 is set at a predetermined apertureAl at the point t5. FIG. 76 shows the position of the rotating disk 59at the point t5. An arrow in FIG. 76 represents a rotating amount fromthe closed end to the position where the aperture Al is set.

The AE pulses are output during the reverse rotation of the AE motor aswell as the forward rotation, i.e., eleven AE pulses are output untilthe rotating disk returns the closed end. The CPU 210 controls the AEmotor controlling circuit 66 to stop applying the driving voltage at thepoint t7 after an elapse a predetermined interval from point 46,whereafter the AE motor 29 is freed (S4379). The point t6 is a time ofthe rising edge of the last AE pulse. The interval between the points t6and t7 is determined so that it is long enough to set the shutter bladesat the closed end from the position of the last pulse.

In the example of FIG. 75, the shutter 27 is switched to be driven tothe closing direction before the shutter has fully opened. On the otherhand, if brightness of an object is low, and the fully opened aperturearea is required, the AE timer time is set longer than that of FIG. 75.In such a case, the AE motor 29 is rotated in the forward direction toopen the shutter 27 until the shutter 27 fully opens and contacts to theopened end, and then after the elapse of the AE timer time, the AE motoris rotated in the reverse direction to close the shutter.

FIG. 77 is a timing chart of the exposure process in the strobe emissionmode. In this mode, the AE timer time T_(AE) and the FM timer timeT_(FM) are determined in S4305 or S4307, and in S4311 or S4313. The AEtimer time, which defines the time period between the reference startpoint t4 and the point t5 at which the applied voltage to the AE motor29 is switched from forward to reverse, is set to a predeterminedconstant time, for instance 1/100 seconds. The FM timer time, whichdefines the time period between the reference starting point t4 and thepoint t4' when the strobe is flashed, is determined in accordance withthe object distance to define the aperture area at the time when thestrobe flashes. Thus, the FM timer time is the time period to define theaperture area in the strobe emission mode.

As shown in FIG. 77, the CPU 210 controls the AE motor controller 66 torotate the AE motor 29 reversely at the point t1 (S4315) and to rotateit forward at the point t3 (S4323). The two timers (AE and FM) arecounted from the reference starting point t4 (S4337, S4379), and the CPUoutputs a strobe trigger signal at the point t4' to start flashing thestrobe (S4353). As the AE motor 29 continuously rotates after flashingthe strobe, the shutter becomes fully opened. During the forwardrotation between the point t3 and the full open position, eighteen AEpulses are output. FIG. 78 shows the position of the rotating disk 59 atthe full open position, i.e., at the opened end. The AE motor controller66 applies the reverse rotation voltage to the AE motor 29 after theelapse of the AE timer time at the point t5 (S4371) and stops to applythe voltage at the point t7 (S4379) and then the AE motor 29 is freed.

According to the above mentioned exposure process, the shutter iscontrolled based on the AE timer time and/or the FM timer time withoutthe need to detect the position of the shutter blades, thus it becomeseasier to control the shutter using the DC motor.

Further, since the reference starting point t4 is set in an intermediaterange of the shutter operation, the rotation of the AE motor is stablewhen it passes the reference starting point t4, and the aperture areadefined by the AE timer time or the FM timer time from the point t4 canbe determined accurately. And also, since the reference starting pointis defined as the rising edge of the third pulse of the AE pulse, andthe first and second pulses are input before the timer starts to countin normal way, the controller can determine whether the AE motor 29 hasstarted to rotate normally when the timer starts to count. This featureavoids power consuming operations, for example, the strobe is notflashed if the AE pulse is not output in the process of FIG. 77.

Furthermore, since the shutter is first rotated in the closing direction(reverse) to contact the closed end and then is rotated in the openingdirection (forward), the initial position from which the shutter startsto open is kept at the same point under all photographing conditions,and allows the AE motor 29 to reach a constant rotation, i.e., therotational speed and/or amount. The aperture area is, therefore,accurately determined in accordance with the AE or FM timer time.

Particularly, in the irregular case where the shutter is stopped at theintermediate range prior to the exposure process as shown in FIG. 79,since the shutter returns to the regular initial position and thenstarts to rotate to open the shutter, the shutter operation is executedin normal way. FIG. 80 shows a time chart in such the irregular case. Inthis case, during the reverse rotation before opening the shutterblades, one AE pulse is output. The period TWT is counted from a risingedge t2 of the AE pulse. The operation after the point t3 of FIG. 80 isidentical to that of FIG. 75.

If the reverse rotation process prior to starting to open the shutter isnot provided, and the shutter is stopped at the irregular initialposition as shown in FIG. 79, the CPU 210 starts to count the AE pulsesto find the reference starting point from the point where the shutterstopped, and the aperture area becomes larger than the required.

The reference starting point is not limited to the third pulse, but thesecond, fourth or another pulse may be also used for defining thereference starting point. For instance, if the shutter blades are openedrelatively quickly with respect to the pulse output timing, thereference starting point may be set to the rising edge of the secondpulse. The pulse number used for determining the reference startingpoint may be stored in the EEPROM 230. The CPU 210 may start to countthe timer time from the rising edge of the AE pulse of the storednumber.

The exposure controlling device of the present embodiment is providedwith the function to compensate for errors of the relationship betweenthe time period and the aperture area on differences of the individualshutters which may comprise the shutter 27. As mentioned above, sincethe device of the embodiment controls the aperture area on the basis ofthe time period, the relationship between the aperture areas defined bythe time periods should be coincident with the designed relationship.For instance, the relationship between the AE timer time and themeasured exposure value Ev for an ideal shutter is shown in thefollowing table 3 according to the designed relationship.

                  TABLE 3                                                         ______________________________________                                        AE data (Ev)                                                                              AE timer time (ROM data)                                          ______________________________________                                        10          9410 μs                                                        11          7132 μs                                                        12          5405 μs                                                        13          4096 μs                                                        14          3104 μs                                                        15          2353 μs                                                        16          1783 μs                                                        17          1351 μs                                                        ______________________________________                                    

The designed relationship is stored in ROM as a default standardrelationship. If an actual shutter has the same characteristics as theideal shutter, the AE timer time can be determined by the initialstandard relationship.

However, the relationship between the AE timer time and the exposurevalue may not be univocally determined due to the individual differenceas mentioned above. FIG. 81 is a graph showing the relationship betweenthe AE timer time and the actual exposure value obtained by the exposurebased on the respective AE timer time. Solid line S1 in FIG. 81represents the characteristic of the ideal shutter that has a designedcharacteristic as shown in the table 3. Broken line S2 and dashed lineS3 represent actual shutters that have differences from the designedcharacteristic.

When the relationship of AE timer time and the exposure value is notdetermined in accordance with the designed relationship (represented byS2 and S3), the aperture area cannot be determined accurately inaccordance with the designed relationship, thus causing poor qualityphotographs. Although it is possible to reduce the individualdifferences by increasing the accuracy of the assembling or mechanicalconstruction, this takes a lot of time for assembling or manufacturing.The exposure controlling device of the embodiment allows forcompensating the differences by the electronic adjustment of thecontrolling system.

The AE timer time is calculated by using a predetermined formula thatincludes the coefficients to adjust the relationship for each individualshutter in the embodiment.

It is assumed that the relationship between the AE timer time T_(AE) andthe exposure value Ev is defined as the following logarithmicrelationship (1).

    Ev=(a*log.sub.2 T.sub.AE)+b                                (1)

The terms a and b are coefficients for adjusting the relationship forindividual shutters which may comprise the shutter 27. The term T_(AE)represents an ideal AE timer time, as shown in Table 3. The AE timertime T_(AE) is calculated by the first relationship (2) in accordancewith relation (1).

    T.sub.AE =2.sup.((Ev-b)/a)                                 (2)

The AE timer time is adjusted by setting coefficients a and b for eachindividual shutter. The individual values of the coefficients are storedin the EEPROM 230 for each individual camera during manufacturingprocess or inspecting process.

The approximate relationship (2) is determined based on a statisticalanalysis of the results of inspections of a plurality of cameras suchthat the good approximation will be obtained. Further, the relationship(1) is not limited to the above mentioned logarithmic relationship.

In general, the individual values (coefficients a and b) have priority.That is, when the individual values are stored in the EEPROM 230, thesevalues are used for calculation. The default values are used whenindividual values are not supplied. When the exposure value Ev is lowerthan 10, the default AE timer time stored in the ROM is used whichcorresponds to the exposure value Ev. Because, in such the case, the AEtimer time becomes longer and the affect of individual differences inthe AE timer time becomes smaller. Accordingly, an accurate adjustmentis not required for these lower values of Ev.

The setting of the coefficients is executed according to the followingsteps. First, a required exposure value Evr is determined based on abrightness value Bv and a film speed Sv. Subsequently, the AE timer timecorresponding to the required exposure vale Evr is determined by usingthe default standard relationship. Next, an exposure value Ev isdetermined in accordance with the AE timer time.

The above mentioned steps are executed at least twice under thedifferent conditions, and the values of the AE timer time and thecorresponding exposure values are substituted to the relationship (1).

Table 4 shows a concrete example of the correspondence between the AEtimer time and an actual exposure value Ev when the shutter iscontrolled with using default standard relationship installed in theROM.

                  TABLE 4                                                         ______________________________________                                        Required exposure                                                                           AE timer time                                                                            Determined                                           value Evr     (ROM data) Exposure value Ev                                    ______________________________________                                        13            4096 μs 11.80                                                16            1783 μs 14.92                                                ______________________________________                                    

In this case, the equations are shown in the followings.

    11.80=(a*log.sub.2 4096)+b

    14.92=(a*log.sub.2 1783)+b

    a=-2.6, b=43.0

The determined coefficients a and b are stored in the EEPROM and the AEtimer time will be determined by the following specific relationship (3)in this concrete example.

    T.sub.AE =2.sup.((Ev-b)/a) =2.sup.((Ev-43)/-2.6)           (3)

The AE timer time determined by relationship (3) are shown in Table 5.

                  TABLE 5                                                         ______________________________________                                        Required exposure                                                             value Evr     AE timer time (EEPROM data)                                     ______________________________________                                        10            6617 μs                                                      11            5071 μs                                                      12            3883 μs                                                      13            2974 μs                                                      14            2279 μs                                                      15            1745 μs                                                      16            1337 μs                                                      17            1024 μs                                                      ______________________________________                                    

Alternatively, the actual relationship between the required exposurevalue and the AE timer time may be stored in the EEPROM instead of thevalues of the coefficients a and b. An appropriate exposure can beobtained by controlling the shutter based on the adjusted AE timer time,even if the characteristics of a shutter deviate from the design valuesdue to mechanical error.

The number of measurement points for determining the coefficients is notlimited to two points (i.e., Evr equal to 13 and 16) as in the aboveexample and the coefficients may be determined by a method in which dataare measured for a larger number of points and the average of theresults are calculated.

The above mentioned principle for adjusting the relationship between therequired exposure value and the AE timer time can be applied byadjusting the relationship between the required aperture value and theFM timer time.

It is assumed that the relationship between the FM timer time T_(FM) andthe aperture value Av are respectively defined as the followinglogarithmic relationship (4) in the embodiment.

    Av=(c*log.sub.2 T.sub.FM)+d                                (4)

The term c and d are coefficients for adjusting the relationship forindividual shutters. From relationship (4), the FM timer time T_(FM) iscalculated by relationship (5).

    T.sub.FM =2.sup.((Av-d) /c)                                (5)

The setting of the coefficients is executed according to the followingsteps. A required aperture value Avr and the FM timer time correspondingto the required exposure value Avr is determined using the defaultstandard relationship. Next, an aperture value Av is determined inaccordance with the FM timer time.

The above mentioned steps are executed at least twice under thedifferent conditions, and the values of the FM timer time and thecorresponding aperture values Av are substituted to the relationship (4)to make equations.

Table 6 shows a concrete example of the correspondence between the FMtimer time and an actual aperture value Av when the shutter iscontrolled with using default standard relationship installed in theROM.

                  TABLE 6                                                         ______________________________________                                        Detected FM data                                                                         FM timer time                                                                             Determined aperture value Av                           ______________________________________                                        4          8000        4.2                                                    8          3000        8.6                                                    ______________________________________                                    

In this case, the equations are shown by the following.

    4.2=(c*log.sub.2 8000)+d

    8.6=(c*log.sub.2 3000)+d

    c=-3.11, d=44.52

The determined coefficients c and d may be stored in the EEPROM 230 andthe FM timer time will be determined by the following specificrelationship (6) in this concrete example.

    T.sub.AE =2.sup.((Ev-b)/a) =2.sup.((Ev-43)/-2.6)           (6)

The FM timer time determined by relationship (6) are shown in Table 7.Alternatively, the actual relationship between the required exposurevalue and the AE timer time can be stored in the EEPROM instead of thevalues of the coefficients. An appropriate exposure can be obtained bycontrolling the shutter based on the adjusted FM timer time, even if thecharacteristics of a shutter deviate from the design values due tomechanical error.

                  TABLE 7                                                         ______________________________________                                        Measured FM data                                                                            FM timer time (EEPROM)                                          ______________________________________                                        Av4           8358 μs                                                      Av5           6686 μs                                                      Av6           5353 μs                                                      Av7           4282 μs                                                      Av8           3428 μs                                                      Av9           2742 μs                                                      ______________________________________                                    

As described above, according to the present invention, the control ofthe open/closed condition of a shutter can be performed by timing, thusthe arrangement of the control system can be simplified even in the casewhere the lens shutter is to be driven by a DC motor. Furthermore, theinfluence of variations among individual cameras in terms of time andaperture area, which can be a problem when performing time-managementtype control, can be corrected by using a prescribed approximationformula and performing a calculation using data set at the time ofadjustment.

The present disclosure relates to subject matter contained in JapanesePatent Application No. HEI 08-058369, filed on Feb. 21, 1996 and HEI08-012317 filed on Jan. 26, 1996 which are expressly incorporated hereinby reference in their entirety.

What is claimed is:
 1. An exposure controlling device for a lens shuttercamera having a lens shutter with shutter blades and a DC motor fordriving said shutter blades to open and close, said device comprising:acontrolling unit that controls, at the time of an exposure, said DCmotor to rotate forward to open said shutter blades and then to rotatereversely to close said shutter blades; a calculating unit thatcalculates a time period between a predetermined starting point and apoint where a predetermined aperture area is obtained during the forwardrotation of said DC motor; and a timer for counting said time period,wherein said controlling unit controls said DC motor to rotate reverselyfor a predetermined time period before the exposure.
 2. The exposurecontrolling device according to claim 1, wherein the motion of said lensshutter is mechanically limited at both ends of the actuation range ofsaid shutter blades, and wherein said controlling unit controls, beforethe exposure, said DC motor to set the shutter blades at the one endwhere said shutter blades are fully closed.
 3. The exposure controllingdevice according to claim 1, further comprising a position detector fordetecting said starting point for counting said timer.
 4. The exposurecontrolling device according to claim 3, wherein said position detectorcomprises a pulse encoder that generates a starting pulse at saidstarting point.
 5. The exposure controlling device according to claim 4,wherein said pulse encoder generates a plurality of pulses, and whereinthe shutter driving actuation and said starting pulse is a predeterminedone of said plurality of pulses.
 6. The exposure controlling deviceaccording to claim 5, wherein said encoder comprises:a photocoupler; anda rotating disk mounted in connection with said photocoupler, saidrotating disk rotating in correspondence with the actuation of said lensshutter by less than one full turn, said rotating disk having a firstangular range within which the output signal from said photocoupler doesnot vary when said rotating disk rotates, and a second angular rangewithin which said plurality of pulses are output from said photocouplerin accordance with the rotation of said rotating disk; wherein saidphotocoupler detects said first angular range before the exposure. 7.The encoder according to claim 6, wherein said second angular range isprovided with a light modulating pattern that is formed as a pluralityof transparent portions arranged on an opaque surface of said rotatingdisk, and wherein said photocoupler comprises a photointerrupter todetect the transmitted light through said transparent portion.
 8. Theencoder according to claim 7, wherein said light transmitting portionare formed as radially-oriented slits that are angularly spaced.
 9. Theencoder according to claim 7, wherein said first angular range isopaque.
 10. The encoder according to claim 7, wherein said transparentportions are formed at in constant angular intervals.
 11. The exposurecontrolling device according to claim 6, wherein the counting of saidpredetermined time period for the reverse rotation before the exposureis restarted when a pulse is output during the reverse rotation.
 12. Theexposure controlling device according to claim 1, wherein saidcontrolling unit controls said DC motor to rotate reversely at the endof said time period.
 13. The exposure controlling device according toclaim 1, wherein said controlling unit controls a strobe to flash at theend of said time period.
 14. The exposure controlling device accordingto claim 13, wherein said controlling unit controls said DC motor torotate reversely after said shutter blades achieve a fully openposition.
 15. An exposure controlling device for a lens shutter camerahaving a lens shutter with shutter blades, said device comprising:a DCmotor for driving said shutter blades to open and close; and acontrolling unit that controls, at the time of an exposure, said DCmotor to rotate forward to open said shutter blades and then to rotatereversely to close said shutter blades; wherein said controlling unitcontrols said DC motor to rotate reversely to set said shutter at apredetermined initial position before the exposure.
 16. The exposurecontrolling device according to claim 15, wherein the motion of saidlens shutter is mechanically limited at both ends of the actuation rangeof said shutter blades, and wherein the one end where said shutterblades are fully closed is said initial position.
 17. The exposurecontrolling device according to claim 15, wherein said controlling unitcontrols said DC motor to rotate reversely for a predetermined timeperiod before the exposure.
 18. The exposure controlling deviceaccording to claim 15, further comprising a calculating unit thatcalculates a time period between a predetermined starting point and apoint where a predetermined aperture area is obtained during the forwardrotation of said DC motor, and a timer for counting said time periodfrom said starting point.
 19. An exposure controlling device for a lensshutter camera having a lens shutter with shutter blades, said devicecomprising:a DC motor for driving said shutter blades to open and close;and a controlling unit that controls, at the time of an exposure, saidDC motor to rotate forward to open said shutter blades and then torotate reversely to close said shutter blades; wherein said controllingunit controls said DC motor to rotate reversely for a predetermined timeperiod before said exposure.
 20. The exposure controlling deviceaccording to claim 19, further comprising a calculating unit thatcalculates a time period between a predetermined starting point and apoint where a predetermined aperture area is obtained during the forwardrotation of said DC motor, and a timer for counting said time periodfrom said starting point.